THE INVISIBLE ENEMY: Boobytraps in Vietnam

Copyright © 1992 by J. Flores Publications

Published by:J. Flores PublicationsP.O. Box 830131Miami, FL 33283-0131

Direct inquires and/or order to the above address.

ISBN 0-918751-23-3

Library of Congress Catalog Card Number: 91-73317

Printed in the United States of America

Table of Contents

Introduction 7

Counter-Measures 15Enemy Mine Indicators 47Explosive Anti-Personnel Devices 65

Non-Explosive Boobytraps 93Water, Anti-Tank & Vehicle Mines 109Anti-Helicopter Mining 137Index 142

Introduction

THE VIET CONG were recognized asmasters in the deadly art of boobytrap con-struction and deployment. During the earlyyears of the US involvement in Vietnam a highpercentage of all American casualties came asa result of this type of warfare.

US Marines landed in force in South Vietnamduring March 1965. During the first months offighting approximately sixty-five to seventy-fivepercent of all Marine casualties were caused bymines and boobytraps. During 1968, 37.7 percentof all Marine casualties were caused by the ac-cidental detonation of a mine or boobytrap.

In the final tally, enemy mines andboobytraps caused approximately seventy per-cent of the vehicle losses and twenty percent ofthe casualties in US forces.

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ENEMY DOCTRINEThe Viet Cong employed "nuisance mining,"

that is, scattering mines throughout an arearather than in well-defined minefields, on ascale never before encountered by US forces.Mines and boobytraps were usually installed atnight by trained personnel who had detailedknowledge of the terrain. Through ingenioustechniques in mine warfare, the Viet Cong suc-cessfully substituted mines and boobytraps forartillery. Instead of conventional minefieldscovered by fire, the enemy hindered orprevented the use of supply roads and inhibitedoff-the-road operations by planting explosivedevices in indiscriminate patterns. While hebenefited directly by causing combat casual-ties, vehicle losses, and delays in tactical opera-tions, equally important was the psychologicaleffect. Just the knowledge that a mine orboobytrap could be placed anywhere slowedcombat operations and forced allied troops toclear almost the entire Vietnam road net everyday.

The Viet Cong employed mines andboobytraps to delay and disrupt the use of roadsand paths and to cause the diversion of USforces to guard and clear those routes. In addi-tion to the threat to military and lawful civilian

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movement, American personnel and equip-ment employed in patrolling the roads and indetecting and removing mines and boobytrapswere prime targets.

In contested areas where friendly offensiveoperations or patrol activities were conducted,the Viet Cong employed mines and boobytrapsto inflict casualties, delay and channelizemovement, damage or destroy equipment andas an outer perimeter defense around under-ground factory entrances.

ENEMY SOURCES OF SUPPLYThe Viet Cong used a very limited number

of modern machine-produced mines. Themajority of enemy mines were handmade bythe Viet Cong using US duds, discarded am-munition and equipment, and materialsthrown away by American forces as trash.Ninety percent of all the material in enemymines and boobytraps were of US origin.

All dud ammunition was a source of supplyfor the Viet Cong. After air strikes and artilleryand mortar missions, enemy salvage teamsmade sweeps to collect duds. Lighter ordnancewas carried away to preparation areas; largebombs and projectiles were broken down andstripped on the spot. In some cases the larger

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duds were rigged as boobytraps where they hadfallen. This was especially true when theenemy felt the strike or fire mission was apreparation for an infantry attack.

However, defective ammunition was notthe only source of enemy supply. Carelesslydiscarded ordnance of all sizes and in anyquantity was collected by Viet Cong salvageteams. Mortar rounds, rockets, LAAWs,grenades, and small arms ammunition aban-doned to lighten the load (or improperlysecured and lost by fast-moving US troops)had value as the explosive element inboobytraps. Even a single M16 round ejectedto clear a stoppage could be used by the VietCong.

Additionally, materials discarded as trashand improperly destroyed such as ration, am-munition, beer and soda cans, batteries,waterproof packaging materials, bandoliers,etc., provided the enemy with a valuable sourceof supply to support his boobytrap and minewarfare operations.

Mines and boobytraps employed by the VietCong against friendly personnel were limitedin type and quantity only by the availability ofmaterials and the imagination of the enemy.Anything that could be made to explode and

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cause injury could be rigged as an anti-personnelmine or boobytrap.

VIET CONG MINE FACTORIESPrimitive Viet Cong mine factories were

usually located in the areas they supplied.Great care was taken in the camouflage anddispersal of these facilities. Usually con-structed underground, effort was made to dis-perse the workshops and storage throughout aseries of tunnels. These limited destruction byworking accidents or US fire and protectedagainst discovery. By the end of 1970, fourthousand-eight hundred tunnels had been dis-covered. Most of the discoveries were madeduring sweep operations by US forces. Tunnelcomplexes were also located through local in-formers and by means of dogs trained to findunderground facilities. At one find, a completeworkshop was discovered. Old hand-crankeddrill presses, along with small forges, heated bycharcoal, to melt scrap metal and sand moldswere used to produce hand grenades.

Plants were planted so they would growaround and on top of doors to the entrances ofthe tunnels. Dried leaves were sometimeschanged every three days before they began todarken and were almost always gathered far

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from the actual factory site. Tunnel entranceswere concealed in villages under such places ascooking fires, animal pens, and latrines. Theavenues of approach to the tunnel entranceswere heavily mined and boobytrapped.

As important as concealment of the minefactory, was the mobility of its personnel andequipment. Even while the mine factory wasbeing settled in one position, new positionswere being prepared for rapid displacement.Rarely did a mine factory remain in one placeany longer than a few weeks. There was nodistinct pattern of movement. Factories wereknown to return to previous positions evenafter that position had been discovered anddestroyed by US forces.

NVA (North Vietnamese Army) trained en-gineers provided the skilled nucleus for theenemy mine factories, but supervision andlabor were primarily Viet Cong.

The typical output of a local Viet Cong minefactory was about 135 mines and explosivedevices per month.

ENEMY TACTICSAs the Americans improved in their ability

to detect mines, the enemy countered with newtwists such as increased use of boobytraps at-

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tached to a basic mine to create casualtiesamong mine-clearing personnel; larger minesburied deeper with reduced activation pres-sure; and pressure electric detonators with of-fset devices to explode mines under vehicles.Command-detonating mines were normallyused in densely populated sections. Theheaviest mining was along lines of communica-tions near fixed installations.

The enemy made every effort to avoidrepeating practices which, when analyzed,could indicate a pattern. Therefore, theVC/NVA doctrine stressed where to use mines,not how.

A few of the kinds of places where enemyanti-tank and anti-vehicular mines could befound were road junctions and the areas in thevicinity of the road near the junction, with allthe mines set to detonate simultaneously.Bridges and the approaches five to fifteenmeters from the bridges. Old wheel and treadtracks in the road, with care taken to dupli-cate the track after mine emplacement. Un-derneath roads, tunneling in from theshoulders. Potholes in the road. Areas recent-ly cleared by Free World military forces. Theenemy replaced the mines that have beentaken out.

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ANTI-PERSONNEL MINES AND BOOBYTRAPSEnemy tactics in emplacing anti-personnel

mines and boobytraps differed from those usedin anti-tank and anti-vehicular mining only bywhere they put them. Locations most common-ly used by the VC/NVA to place anti-personnelmines and boobytraps were: narrow passages,paddy dikes, trail junctions, hedgerows andtree lines, tunnels and caves, fence lines andgates, tree branches overhanging trails, likelycommand post sites, high ground andridgelines, shady areas, stream fords, wells andnatural watering points on streams and rivers,and likely helicopter landing zones.

Any place where US troops frequentlywalked, took cover, rested, or drew water wasa likely location for enemy anti-personnelmines and boobytraps.

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Counter-Measures

In response to the massive use of minesand boobytraps by the Viet Cong, a con-centrated effort in strategic and tactical plan-ning, research and analysis, and materialdevelopment was focused on counter-measuresfor these devices. Extensive study of Viet Congand North Vietnamese mining operations,techniques, and ordnance were conducted byseveral branches of the US Armed forces. Inaddition, a materiel exploitation programevolved.

The Combined Material Exploitation Cen-ter was charged with collecting and exploitingcaptured material of all types including minesand boobytraps. This entailed examination,identification, analysis, evaluation of the itemsand distribution of the information obtained.

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The characteristics, capabilities, andlimitations of the enemy materiel were deter-mined, so that adequate counter-measurescould be devised. The Mobility Section of thisorganization evaluated and analyzed minesand boobytraps.

When captured or otherwise obtained,items of interest were tagged and sent to thecenter for full-scale examination. Quick-reac-tion or "go" teams were airlifted to objectiveareas to conduct on-site examinations of cap-tured material determined to be of immediatetactical importance. When evacuation was im-possible, either because of the tactical situationor the size of the item, all important data wererecorded and, along with photographs orsketches, were forwarded to the center foranalysis and examination.

The mining problem was divided into threemajor categories: road mining, off-road anti-vehicular mining, and anti-personnel mining.Most US mine casualties occurred during roadclearing operations. Heavy losses coupled withthe need to clear many kilometers of road everyday put a strain on the engineer and combattroop effort. Off-road mines caused moredamage to armored vehicles than road miningdid. Little used trails and tracks, open fields,

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jungles, and even avenues that were difficultfor vehicles to use were mined. The anti-per-sonnel mines and boobytraps were ingeniouslyrigged devices, set in unusual locations to trapthe individual soldier. From an extensiveanalysis of the techniques used by the enemyin each of the four corps tactical zones, a mapwas drawn showing the areas where miningactivity was heavy and qualifying each area byindicating the most common type of mine there.

In the III Corps Tactical Zone, the Viet Congseemed to adjust their mining pattern accord-ing to US tactical operations, rather than fol-lowing a preconceived plan. During periodswhen US forces activity was high, there was asubstantial increase in the Viet Cong miningefforts. In this particular zone, intelligencesources learned that the mining and setting ofboobytraps was largely the work of Viet Conglocal forces rather than larger Viet Cong or NVAunits.

Counter-measures were those actions, bothtactical and non-tactical, that could be taken byunits or individuals which reduced the mineand boobytrap threat. Counter-measuresdecreased the enemy's ability to place minesand boobytraps or limited their effectiveness ifthey were placed.

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NON-TACTICAL COUNTER-MEASURESThe most effective way to counter the Viet

Cong's mine and boobytrap threat was todestroy his threat at its source; i.e., the elimina-tion of the VC/NVA mine and boobytrap fac-tories and the sources of supply for these fac-tories.

Every effort was made to locate existingenemy mine and boobytrap factories, whichmany were located in tunnel complexes, and todetermine likely locations for future factorysites. Hoi Chanhs (Viet Cong defectors), POW'sand captured documents were carefullyprocessed because, with skillful handling, theyprovided vital information on factory locationsites.

Once found, Tunnel Rat teams, armed onlywith a flashlight, knife, and handgun wouldclear and explore tunnels. The burning-typetear gas grenades, known as CS grenades,along with HC smoke grenades, were also usedin conjunction with the M106 Riot ControlAgent Dispenser, dubbed Mity Mite, a portableblower, to clear tunnels of the enemy. Thissystem was capable of forcing the enemy out ofunsophisticated tunnel complexes, as well ashelping to locate hidden entrances and airvents. The Mity Mite system could not drive

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personnel from the more complex, multileveltunnel systems, many of which contained air-locks. Existing factories and future locationswere then made unusable.

After tunnels were cleared and searched,they were destroyed to prevent their furtheruse by the enemy. Methods developed to keepthe tunnels from being used again includedplacing riot control agents in the tunnel, seal-ing the entrance with explosives, using demoli-tions to destroy the tunnels, pumping acetylineinto the tunnel using blowers and igniting thegas by explosives, and using constructionequipment to crush the tunnels.

However, bulk CS was widely used in tunneldenial operations, in which bags of CS wereexploded throughout the tunnels. In some casesthe tear gas remained effective for five to sixmonths if the tunnel was sealed.

More important than neutralizing theenemy's mine and boobytrap factories, was thedenial to the enemy of the source of supply withwhich he operated these factories; i.e., unex-ploded US ordnance, discarded equipmentand improperly destroyed trash. The fact thatUS ordnance and salvageable trash fell intoViet Cong hands could be traced to severalfactors.

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UNEXPLODED ORDNANCEThe first factor and an important source of

unexploded ordnance for the Viet Cong wasprovided by the free world military force'semployment of air, artillery and naval gunfiresupport. Some ordnance items failed todetonate, became a "dud" and provided a poten-tial mine or boobytrap. All American personnelwho employed fire support were instructed toconsider this fact in the employment of support-ing arms, and to be careful not to call for firesin excess of what was required to accomplishthe mission.

ABANDONED MUNITIONSThe second factor, another important source

of explosive material supply for the enemy'smine and boobytrap operations, were aban-doned or lost munitions. Examples of this prob-lem which assisted the Viet Cong in their ef-forts were:

Overstockage. A unit overstocked ammuni-tion and then was required to move on shortnotice with only a basic load. The remainingammunition was left on the abandoned positionand recovered by the enemy.

Inadequate ammunition handling proce-dures. A unit attempted to turn in excess am-

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munition to an ASP (ammunition supply point)and was refused due to inefficient disposal pro-cedures.

Abuse of Ammunition. A unit discarded am-munition considered unserviceable because ofdirt, tarnish, mud or other avoidable conditionsor minor imperfections.

Loss in Transit. A helicopter sling broke onan ammunition resupply mission and all orportion of the load was scattered across thecountryside.

IMPROPERLY DESTROYED TRASHThe last factor, but far from least impor-

tant to the Viet Cong's mine and boobytrapprogram, was his source of supply fromfriendly trash. All items considered unusableby free world forces should have been com-pletely destroyed or properly disposed of, butmany weren't.

Discarded C-ration/soda cans were com-monly used in a type of boobytrap that wasconstructed with a M26 grenade. The safetypin from the grenade was removed and thegrenade was put in the can. When the can wasdisturbed, the grenade slipped out, the spoonpopped and the grenade detonated.

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VIP PROGRAMThe VIP (Volunteer Informant Program)

proved to be an effective counter-measure tothe enemy's mine and boobytrap efforts. Thisprogram rewarded Vietnamese individualswith cash who turned in dud and abandonedmunitions, or reported the location of mines orboobytraps.

This program significantly decreased theViet Cong capacity to employ US ordnanceagainst free world forces. During one period,188 of 259 payments in the III MAF area weremade to children who turned in explosivesuitable for the manufacture of boobytraps. In1968 alone, 103,521 pieces of ordnance thatcould have been used as mines and boobytrapswere located.

TACTICAL COUNTER-MEASURESTactical counter-measures employed by

US troop were very effective in reducing theViet Cong's capability of emplacing mines andboobytraps when such counter-measureswere aggressively planned and executed.Unit commanders had several tacticalmeasures at their disposal, including theemployment of sophisticated electronicdevices.

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GSR (ground surveillance RADAR) werecrew serviced RADARS that could penetratesmoke, haze, fog, light rain and light foliage todetect and accurately locate moving personnelor vehicles for rapid engagement. They wereused to monitor avenues of approach, bridges,road junctions, barriers and obstacles to detectand report enemy breaching attempts. Monitorpossible rear and forward area drop or landingzones. Search enemy-held terrain and areasbetween friendly and enemy forces to detectmovement. When detected, enemy forces couldbe engaged by ground forces, air raids, andmortar and artillery fire. The maximum rangeof the ANVPPS-4 radar was 1.5 kilometer, whilethe AN/PPS-5 had a range of five kilometers.

Remote Sensors collected real-time combatinformation, intelligence and target acquisi-tion data. Sensors were placed in areas of ex-pected enemy activity and monitored by teamslocated with US forces in forward areas. Move-ment of enemy forces within the sensor detec-tion radius was detected and indications trans-mitted to the monitoring team. This data wasthen analyzed by the team and the resultinginformation reported. Sensors monitoredroads, trails, road junctions, bridges, possibleassembly areas, drop and landing zones.

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The movement of personnel or vehicleswithin the detection radius of the sensor sentvibrations through the ground to the sensor.These vibrations were sensed and a signal wastransmitted to the monitoring device. Seismicsensors detected personnel movement up totwenty-five meters and vehicle movement up toeighty meters from the sensing element.

Acoustic sensors worked on the principle ofmicrophone and had detection capabilitiessimilar to that of the human ear. Acoustic sen-sors were used with seismic sensors and ac-tivated only after receiving a specific numberof seismic activations within a specific period.

Magnetic sensors operated by detecting dis-turbances in the earth's magnetic field createdby movement of iron-based metal near the sen-sor.

Electromagnetic sensors radiated a con-tinuous radio frequency (RF) signal that set upan active field around the sensor. Movement ofobjects within the field affected the emittingantenna's signal properties. When these chan-ges were sensed, the sensor transmitted anactivation signal. Electromagnetic sensorswere used in marshy areas, waterways, depres-sions, and gullies where seismic sensors wereineffective.

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Sensors were either hand placed or airdropped by helicopters.

Maintaining a constant physical presencethroughout the TAOR (Tactical area of respon-sibility), that included outposting of key roads,was the most effective tactical counter-measure. It was, however, sometimes difficultto achieve because of the number of troopsrequired to ensure good coverage.

Conducting aggressive patrolling kept theViet Cong off balance. These included LongRange Patrols (LRP); they were needed in Viet-nam because of the difficult terrain and theelusiveness of the enemy. LRP units wereformed based on the success of the 5th SpecialForces Group's Project Delta. These LRP teamsmonitored trails and suspected river crossingsites. Taking prisoners of war was an addition-al mission of these patrols. The POW's werethan interrogated to find mine and boobytrapfactory locations.

Reconnaissance patrols were often con-ducted by units ten or fifteen minutes after amine sweep to surprise the enemy who wouldlay mines behind the team.

One of the most effective counter-measurewas the employment of scout-sniper teams.Sniper teams consisted for the most part of two

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men; a sniper and a spotter. The sniper wasarmed with an accurized M14 rifle with asniper scope mounted. The most successful useof the sniper was with ambush patrols. Sniperswould either accompany a platoon on an am-bush or, when provided with a security elementof five to eight men, established their own am-bush-sniper position. They were situated inmany cases near known or suspected ricecaches or tunnel entrances. Using such tactics,the sniper picked the time and place to engagethe enemy, thereby maintaining the initiative.

In addition, sniper teams were sometimesleft behind to engage Viet Cong who were fol-lowing a moving unit. The team establishedpositions that would allow long-range observa-tion over the route that the unit had traveled.This technique was effective because the snipercould engage targets as far away as 900 metersand because the Viet Cong tended to be laxabout their cover at extreme ranges. Thus, theViet Cong presented excellent targets.

Snipers also could operate at night with thehelp of "pink light," an infrared searchlightthat illuminated an area for a person lookingthrough an infrared scope or by using a star-light scope. The starlight scope intensified theavailable light, from the moon and stars, rather

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than emitting a light source of its own. Insituations where no natural light was availablefor the Starlight scope, artificial illuminationfrom searchlights, flares, and other light sour-ces were used. These scopes allowed the sniperto operate anytime of day or night, especiallyconsidering that the Viet Cong placed most oftheir mines and boobytraps during the night.The stay-behind sniper teams consisted of twosnipers, a radio operator, and three men forsecurity.

Small unit cordon and search operations incoordination with Vietnamese units and policegathered intelligence and Viet Cong suspects.Troops would surround and seal-off a village.Then teams of intelligence officers and Viet-namese police would search the village, houseby house, for Viet Cong suspects. Each teamwas composed of six Police Field Force mem-bers with scout dogs. They were trained tosearch for hidden documents, weapons, andother items that were stored in caches by theViet Cong. All members of a household weresearched and identifications checked.

A screening center was established at acentral location within the village wheresuspects were questioned and checked againstphotographs of known Viet Cong suspects.

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Suspects detained were taken to police head-quarters for further questioning. While thesearch was being conducted, civic action, suchas medical treatment to the sick or giving treatsto the children, was performed.

H&I (harassment and interdiction) firesover roads or over specific areas discouragedthe enemy from emplacing mines andboobytraps. The fires used mechanical, time-fuzed projectiles set to burst approximatelythirty feet off the ground at ranges of onehundred to one thousand meters. Light andmedium artillery (105mm and 155mm) andalso eight-inch howitzers were used.

Another technique that was also used wasthe artillery ambush. The ambush involved theemplacing of a homemade trip flare device withthe tripwire running across the road or trail.An artillery unit was laid on this grid and firedon the flare signal. Two flares of different colorswere used to determine the direction of travelof the target, so that appropriate fire could beplaced at either side of the location.

Small stay-behind patrols were employed aseffective counter-measure. These teams wereusually dropped off unnoticed from units pass-ing near a road. At other times, both a unit anda stay-behind team would be airlifted into a

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landing zone together. The unit was sub-sequently withdrawn, leaving the team as astay-behind patrol. While on patrol, some unitswould leave a small team behind at the unit'sovernight position. This team would pick-offthe enemy who came to scavenge the positionfor useful items.

Another technique was to boobytrap thetrash left by a unit. In one incident, a unit thatknew it was being followed by a small group ofViet Cong, boobytrapped the trash it left be-hind. A pressure-release fuzed mine was placedbeneath a case of C-rations that was buriedwhere the unit had camped overnight. Twentyto thirty minutes after departing, a small teamreturned to the area and found the bodies ofseveral VC killed by the mine.

Paving or oiling dirt roads prevented theViet Cong from easily concealing mines as theywould have to dig a hole through the pavementor disturb the oiled dirt. A good example washeavily mined Route 1 in Quang Ngai Province.Although culverts were still destroyed by theenemy, there were no mining incidents afterthe road was paved.

Tanks were used to discourage the laying ofmines. In December 1966 an armor unit wasassigned to secure the route from Tay Ninh to

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Tri Tam, where small groups of Viet Cong hadbeen successfully mining the road. The bat-talion commander chose to use the "thunderrun" technique to offset this enemy action.During the hours of darkness, a tank companyor platoon "ran the road" two or three times atirregular intervals. It fired canisters and .50caliber and 7.62mm machine guns at likelyenemy locations on both sides of the road. Afterthree nights, mining incidents stopped, and thefirst Chieu Hoi rallier surrendered. He at-tributed his action to the thunder runs. Thistechnique was used by most of the tank unitsin Vietnam.

Using the native ability of the Kit CarsonScouts, coupled with their knowledge of thearea of operations and Viet Cong activities,proved highly useful in locating devices.During October 1968, Kit Carson Scouts found229 mines and boobytraps in the III MAF area.Kit Carson Scouts were former Viet Cong whohad deserted to the American side.

Removing all vegetation from the sides ofroads and around base camps eliminatedenemy cover and concealment. The equipmentthat filled the need for a rapid, efficient landclearing device was the Rome K/G ClearingBlade—better known as the Rome plow. It con-

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sisted of a tractor attachment with a blade that"stung" and "sliced" large trees. A sharp projec-tion on the left side of the blade split the trees,while the cutting edge sheared them off atground level. Bulldozers equipped with thisblade would clear both sides of a road from onehundred to two hundred meters.

Herbicides, although they were in the cen-ter of much controversy, were also used for landclearing. For small areas such as base campperimeters and possible ambush sites, helicop-ters or ground-based equipment were used.

The two agents most commonly used inVietnam were Blue and Orange, so named forthe color markings on the containers in whichthe herbicides were shipped. Orange was amixture of two relatively common herbicidesand was classified as a systemic herbicide. Assuch it was absorbed into the plant from thepoint of application. Once inside the plant'ssystem, Agent Orange interfered with thegrowth processes, such as photosynthesis, andeventually killed the plant if the dose was ade-quate.

Blue was a desiccant, contact herbicide thatdamaged plant tissue at the point where it wasapplied. Desiccants are drying agents thatcause leaves to drop off but will not necessarily

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kill the plant itself. In Vietnam, on the average,new foliage grew back within thirty to ninetydays after applying Agent Blue. Captured VietCong admitted that in many instances, theirunits avoided defoliated areas and would notcamp in them. They feared detection by air.

Specially trained scout dogs were used todetect the scent left by the individual emplac-ing a mine or boobytrap. This scent was detec-table one to four days after emplacement. Sinceboobytraps were generally placed shortly afterinitiation of friendly operations, the chance ofdiscovery by dogs was good.

A scout dog team consisted of one dog andone handler, trained to work together and in-separable for operational purposes. Scout dogswere German shepherds and normally workedon a leash.

A trained dog used his vision to detect trip-wires and unnatural elements, and his hearingto detect sound waves created by tripwirevibration. Many dogs detected a tripwire whenit touched the body hair of their forelegs orchest. Most dogs were agile enough to backaway before the device was tripped.

Of 119 dogs killed in South Vietnam be-tween January 1967 and June 1969, only sevenwere killed by boobytraps.

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Helicopter units experimented with avariety of lighting systems to deny the enemyfreedom of movement at night. The earliestsystems were known as the Helicopter Il-lumination System (Lightning Bug-Firefly)and were characterized by a fixed bank of C-123landing lights mounted in a gunship. The crewwould find and hold the target with the lightswhile other gunships engaged the enemy. In theMekong Delta an OV-1C Mohawk was oftenused as part of the team, locating targets by aninfrared device and vectoring the light shiponto the target. A series of refinement weremade which included developing a focusing ar-rangement for the illumination system, testingvarious searchlights, and using the night ob-servation device as a passive means of detec-tion.

When the Cobra was introduced into Viet-nam, the UH-ID/H Nighthawk was developedin the field. The basic components of the Nigh-thawk were an Xenon searchlight, a coaxiallymounted night observation device, and an7.62mm minigun system. The searchlightprovided both white light and infrared, whilethe minigun system mounted in the cargo com-partment allowed the Nighthawk to engage thetarget or provide suppressive fire.

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Normal use involved a Nighthawk and oneor two AH-1G gunships working either an areaor specific targets already pinpointed throughother methods. The Nighthawk would fly atfifty knots five-hundred feet above the terrainwith the gunships to the rear at about 1,500feet. When the light ship detected a target withinfrared light, it could either turn on the whitelight or open fire with the minigun, with theaccompanying gunships then firing into theminigun's tracer pattern. Nighthawks wereemployed to a limited extent in checking outradar sightings, in sensor activity, and inmechanical ambushes.

The effectiveness of these aircraft, evenwhen operating at night, was limited, becausethe noise of the aircraft warned the enemy ofits approach and gave them time to hide.

When all the tactical elements were usedtogether results were positive. One Army unitin the III Corps Tactical Zone made a detailedstudy of the enemy road mining patterns. Theanalysis showed that fifty percent of such ac-tivity in the area of operations was con-centrated in four sectors of road having a totallength of about 4.5 kilometers. Once the prob-lem areas were isolated, sensor fields wereinstalled and ambush patrol activity was in-

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creased. Artillery concentrations were plotted,night aircraft equipped with infrared lightswere put on alert, and night observationdevices were positioned so that the unit couldrespond to sensor activations and patrol sight-ings. After only one month the results wereconclusive. The four road sectors, which hadpreviously experienced fifty-six mining inci-dents per month, had only fifteen incidentsduring the test month. One sector went fromfifteen to one.

INDIVIDUAL COUNTER-MEASURESIndividual counter-measures were those

measures each and every US soldier could taketo diminish the effectiveness of a mine orboobytrap device that had been placed, and wasfound or was accidentally detonated. This couldbe accomplished through physical protectivemeasures, detection and destruction measures,avoidance of explosive devices, and throughapplication of immediate action when an ex-plosive device had been accidental lydetonated.

PHYSICAL PROTECTIVE COUNTER-MEASURESThe individual soldier could have taken these

steps to reduce the effectiveness of enemy mines:

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Wearing body armor and helmet.Sandbagging vehicle flooring. When pos-

sible, a heavy rubber mat was placed over thesandbags to help reduce secondary fragmentssuch as shrapnel, sand, stones and pieces ofsandbag.

Kits were developed for armored personnelcarriers to provide supplemental armor for thehull bottom and to relocate and strengthen thefuel line. One armored personnel carrier onwhich the armor kit was installed hit a twen-ty-pound mine with no casualties among themen on board.

Keeping arms and legs inside vehicles toachieve maximum protection from thesandbags. In many cases, particularly in densefoliage, the troops did better to remainmounted and assault the objective as the car-riers detonated anti-personnel mines andboobytraps.

Maintaining proper distance from otherpersonnel. An analysis of mine and boobytrapdetonations revealed that most often multiplecasualties had occurred. This indicated thatthe soldiers were bunching up and not keepingthe fifteen meter interval.

Not picking up or touching what appearedto be attractive "souvenirs". The VC/NVA

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preyed upon the natural curiosity of US sol-diers and their desire to take home a souvenir.That "souvenir" was most likely a boobytrap.

DETECTION COUNTER-MEASURESDetection of most boobytraps was usually

by visual inspection. The best mine andboobytrap detector was an alert and observantindividual. Each soldier knew the areas inwhich boobytraps and mines were normallyfound and was alerted for things that "just don'tlook right."

Examples were mud smears, mud balls,dung, or a board on the road. Apparent roadrepair, new fill or paving patches, ditching orculvert work. Wires leading away from the sideof the road.

Tripwires across the trails; along shouldersof roads at likely ambush sites; across vegeta-tion; at fords, ditches and across rice paddydikes.

Terrain features that did not appearnatural. Cut vegetation dried and changedcolor; rain washed away covering material andcaused an explosive device to sink leaving asurface depression; a covered device may haveappeared as a mound. Suspicious items intrees, branches, or bushes.

37

THE INVISIBLE ENEMY

Markings used by VC/NVA to indicate thelocation of a mine or boobytrap.

Probing. Suspicious spots were carefullyprobed with a probe or bayonet.

Mine detectors. Mine detectors weredesigned to assist the individual soldier in adetailed, deliberate sweep of a specific area,usually a road. Particular attention was givento the time factors of the individual sweepingsituation, since overhasty opening of a roadmeant an ineffective sweep and quite possiblydestruction or injury to vehicular traffic andpersonnel. The average sweep rate varied fromalmost nothing to about 5 mph depending, ofcourse, on the proficiency of the team and num-ber of contacts encountered.

Various hand-held infrared detectors andothers for use in helicopters and vehicles weredeveloped and tried. Experiments were con-ducted to induce current in mine detonatorwiring using radio frequencies. These experi-ments, however, were unsuccessful and wereterminated.

In using detectors, certain considerationswere kept in mind.

Graveled roads made it difficult for thedetector to discriminate between real and falsetargets.

38

THE INVISIBLE ENEMY

Metallic debris, such as can tops, smallarms ammunition cases, and metal fragmentsfrom artillery rounds fired over roads at nightto discourage mine laying, made it difficult forthe detector to discriminate between real andfalse targets. One method that combated thisdifficulty was to use the same minesweep teamevery day on the same stretch of road. The menbecame so familiar with the road that they wereable to spot minor changes in the surface or thesurrounding area. The majority of mines foundwere detected visually and destroyed with ex-plosives in place.

The tendency for the Viet Cong to burymines deeper than designed detection depths,and to deliberately plant metallic debris in theroad, called for additional caution in the use ofdetectors.

Operator fatigue. Consideration was givento the fatigue experienced by operators aftertwenty minutes of wearing detector earphones.This condition could be delayed from one or twohours by wearing earphones over the helmet sothat two to four inches existed between ear andphone. This also permitted the operator to heara verbal alert for an ambush.

Use of the Buddy System. This system wasnot only useful in training inexperienced sol-

39

THE INVISIBLE ENEMY

diers, but also provided an extra margin ofsafety to the individuals who employed it. Twosoldiers working together, in the same area,had the advantage of increased detectioncapability, mutual reassurance, and sharedknowledge.

DESTRUCTION COUNTER-MEASURESOnce detected, mines and boobytraps were

marked or destroyed in place by the discoveringperson or unit to prevent accidental detonationby a following unit or individual.

Mines and boobytraps were not moved un-less absolutely necessary and then only byqualified EOD (explosive ordnance disposal) orengineer personnel. Many boobytraps werethemselves boobytrapped, and if disturbedwould detonate the associated device.

Explosive devices were usually destroyed byengineers. If engineers were not available, thendevices would be destroyed by selectedqualified personnel within each unit.

Mines and boobytraps were destroyed orneutralized by use of grappling hooks,demolitions, and artillery fires. The LVTElinecharge and the LVTE with plow-shapedmine excavator were used in areas of highmine density.

40

THE INVISIBLE ENEMY

The ENSURE 202 Tank-Mounted Expend-able Mine Roller was tried in Vietnam as amine-detonating device. Designed to exert highground pressure without crushing roads andbridges, it was attached to a medium tank. Likethe many rollers used in Vietnam and earlier,the problem was to survive the mine itdetonated. Apparently in many instances it didnot.

AVOIDANCE COUNTER-MEASURESStrict application of training and careful

planning of movements through danger areasenabled unit commanders and individuals toreduce casualties by simply avoiding the ex-plosive devices. Some suggested means foravoiding mines and boobytraps were:

Staying off trails, footpaths, cart tracks, orother likely routes of travel as much as pos-sible. Varying routes used to villages and keyterrain features. Using the same route twicewas an invitation to the enemy to employboobytraps. Keeping the VC/NVA guessing asto which route would be used next.

Moving where local inhabitants moved.These people knew the location of most minesand boobytraps and would avoid these areas.In villages, staying near the villagers and

41

THE INVISIBLE ENEMY

watching which buildings they used. Usinglocal Vietnamese as guides whenever possible.Having sufficient money on hand to pay forinformation on mine and boobytrap locations.

Avoiding patterns and constantly changingdirection of movement. Checking times ofdeparture and return of patrols to ensure, forexample, that all daylight patrols didn't returnbefore supper and all nighttime patrolsdeparted after supper. Avoiding the repeateduse of the same bivouac areas.

Maintaining intervals of fifteen metersbetween men and one hundred meters be-tween men and tracked vehicles. In view ofthe fact that the effective casualty radius ofthe M26 grenade is fifteen meters, and thattwo or more casualties were suffered for eachboobytrap grenade accidently detonated, themaintenance of proper interval was most im-portant.

Moving slowly. Rapid movement generatedcarelessness. A unit should have been allowedsufficient time to move to its objective.

At times the enemy would show themselvesonly when they wanted to be seen. So when UStroops pursued the enemy, they had to be espe-cially alert for deliberately placed boobytrapson the axis of advance.

42

THE INVISIBLE ENEMY

Artillery and mortar fires near and into thearea of operations did not only discourageboobytrap emplacement, but also wouldneutralize devices by sympathetic detonation,overturning and burying placed mines, andrupturing tripwires. Employment of these firesbesides road, before and during a road sweep,discouraged command detonation of roadmines.

A lightweight stick (bamboo) or a slendersteel rod was helpful if used to feel for tripwires.

Marking detected mines and boobytraps sothose following would avoid them.

Helicopters could and were used to extracta unit that found itself in a heavilyboobytrapped area. EOD personnel with detec-tors were flown in to sweep a path from thehelicopter to the trapped individuals. This pathwas marked with tape to enable the soldier toreach the helicopter safely.

At times, the flanks of a road wereboobytrapped out to 250 meters as an obstacleto road sweep security teams. Tanks, precedingthe infantry, could detonate these boobytraps.When situation permitted, tanks moving offand parallel to the road sweeps also reducedtank road mining incidents. Random selectionof tank travel between road and adjacent ter-

43

THE INVISIBLE ENEMY

rain kept the NVA guessing as to the actualroute the tank would take.

When on roads, staying in the well-usedportion and off shoulders. Following the tracksof the vehicle ahead. If there was no vehicleahead, staying out of the ruts. Avoiding holes,depressions, and objects lying on the road.

A boobytrap that was easily detected weresometimes used as a ruse resulting in detona-tion of other explosive devices placed nearby.

IMMEDIATE ACTION TAKEN IF AN EXPLOSIVEDEVICE WAS TRIPPED

It was recognized that little reaction timeexisted once the detonation chain started. Themaximum delay for the M26 and foreigngrenades ranged from four to nine seconds. Ifthe delay element had been modified, the min-imum fuze delay could have been less than 1.5seconds. However, since the time availablecouldn't be predicted, certain immediate actionassisted in reducing casualties and the degreeof personal injury.

IMMEDIATE ACTION DRILLFirst: Being alert for the "pop" of theexploding cap, the tug of the tripwire,or the warning of another individual.

44

THE INVISIBLE ENEMY

Second: Sounding a warning so thatothers could take cover.Third: Dropping to the ground imme-diately.

The immediate action drill was designed asan instinctive reaction based on minimum fuzedelay. Further instructions included:

Not attempting to out run the explosion. The800 fragments of the M26 grenade had an ini-tial velocity of over 5000 feet per second.During the available delay, however brief, anindividual could best remove himself from thecone of the explosion by dropping to the ground.

Presenting the smallest target to the forceof the explosion by pointing the feet in thedirection of the charge. All those nearby shouldhave dropped to the ground when the warningwas sounded.

Not immediately rushing to the aid of in-dividuals wounded by mines or boobytraps.Frequently there was a second boobytrap nearthe first. The man nearest each casualty wouldcarefully clear his way to the wounded in-dividual and render first aid.

Conducting a brief but careful search forother explosive devices in the immediatevicinity before moving on.

45

THE INVISIBLE ENEMY

If a device was tripped and did not explode,following the same immediate action drill andthen blowing it in place.

46

Viet CongMineIndicators

IF THE ENEMY placed mines or boobytrapsin the vicinity of villages or in areas where hemoved or expected to move, he often indicatedthe location or direction of the explosive devicesin some manner. The VC/NVA may not havealways followed the examples in this publica-tion in absolute detail, but as a general rule,the indicators were usually found in regularpatterns such as sticks and stones in a line orsticks placed on or in the ground. Thisregularity of pattern was the danger signal.Any arrangement of sticks and stones whichappeared unnatural indicated a strong pos-

47

THE INVISIBLE ENEMY

sibility of the presence of mines andboobytraps. The illustrations which follow areexamples of marking patterns indicating thepresence of mines and boobytraps which wereencountered in South Vietnam.

48

THE INVISIBLE ENEMY

ARROW MARKERSThree sticks were placed on the trail in the

form of an arrowhead. The important thing toremember was that the point of the arrow didnot always point in the direction of theboobytrap. The symbol could only be consideredas a means to identify an area as beingboobytrapped.

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THE INVISIBLE ENEMY

ARROW MARKERS (con't.)A variation of the three-stick arrowhead

showed a fourth stick. Again, no definite pat-tern was established as to the direction or thereason for the fourth stick (usually broken).But it did mean boobytraps in the area.

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THE INVISIBLE ENEMY

ARROW MARKERS (con't.)The "Y" arrangement was sometimes found

farther down the trail from the arrowhead in-dicating the limit of the danger area. No pat-tern or specific distance was ever established.

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THE INVISIBLE ENEMY

BAMBOO RECTANGLE MARKERAs shown, this marker usually indicated a

boobytrap within the square. Most of thesesymbols found had been laid out with bamboo18 to 42 inches in length.

52

THE INVISIBLE ENEMY

BAMBOO MARKERA piece of bamboo 6 to 8 inches long was

stuck in the ground at an angle of 45 degrees.Generally, boobytraps could be expected alongthe axis of the bamboo in either direction.

53

THE INVISIBLE ENEMY

BAMBOO TRIPOD MARKERThe bamboo tripod consisted of bamboo,

usually about 18 inches long, tied together toform a tripod. Wire, vines, cord or string waswrapped around the legs near the bottom tohold the tripod in place. This device was founddirectly over punji pits, boobytraps, and mines.

54

THE INVISIBLE ENEMY

BROKEN BUSH OR STICK MARKERSA. The Viet Cong were known to break the

tops of small saplings and bushes pointing thebroken part in the direction of theboobytrapped area. Usually mines andboobytraps were planted 50 to 100 meters fromthis marker.

B. A stick or length of bamboo broken at aright angle and lying across the road or trailcould mean an enemy mine or boobytrap 200 to400 meters ahead.

55

THE INVISIBLE ENEMY

BANANA LEAF MARKERSA banana leaf or other similar leaf was

folded down the center with a thin stick ap-proximately the thickness of a toothpick woventhrough in two places. In addition to markingmines, this could indicate an ambush area.There was no pattern as to location or distanceof mines or ambushes from this marker.

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THE INVISIBLE ENEMY

PARALLEL STICK MARKERShort sticks or lengths of bamboo laid paral-

lel to a road or trail usually meant the road ortrail was free of mines or boobytraps.

57

THE INVISIBLE ENEMY

GROWING GRASS MARKERGrowing grass was sometimes tied to form

four growing sheaves of grass. The tied sheavesformed a square of about 6 feet. The mine wasburied or concealed in the center of the square.

58

THE INVISIBLE ENEMY

TRAIL MARKERSThese devices were used extensively

together. The mine or boobytrap was placed(buried) under two large leaves. In front and tothe rear, at no special distance, stakes weredriven. The markers have also been used inde-pendently of each other at times.

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THE INVISIBLE ENEMY

FORKED-STICK MARKERA forked stick was driven vertically into the

ground and another stick laid into the fork withthe elevated end pointing to the danger area.This sign could also indicate enemy direction ofmovement.

60

ROCK MARKERSVarious formations of rocks and small

stones were used to mark boobytrapped areas.

THE INVISIBLE ENEMY

SPACED-STICK MARKERThree sticks, one on each side of a road or

trail and one in the middle, usually meant theroad was not to be used. A mine or boobytrapwas usually 200 to 400 meters from the marker.Stones were sometimes also used in the samemanner.

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THE INVISIBLE ENEMY

TRACK MARKERThe Viet Cong capitalized on the habit of

American troops of following old vehicle tracksby placing mines in these tracks. Mines weresometimes marked with crossed sticks or anarrangement of stones. The location of the minein relation to these markers was unpredictable.The mine could be under the marker or up to400 meters farther on.

63

THE INVISIBLE ENEMY

STAKES WITH X-MARKERAn M1A1 anti-tank mine with ap-

proximately twenty-five pounds of TNT wasdiscovered under this marker. The mine hadbeen marked with stakes at each corner andthree sticks forming an "X" over the mine.

64

ExplosiveAnti-PersonnelDevices

MINES AND EXPLOSIVE boobytrapsemployed by the Viet Cong against Americanforces were limited in type and quantity onlyby the availability of explosive materials andthe imagination of the enemy. Anything thatcould be made to explode and cause injury couldbe rigged as an anti-personnel mine orboobytrap.

Anti-personnel mines and boobytraps werevery successfully employed by the VC/NVA.Part of this success was because US troops werenot familiar with the physical description ofexplosive devices normally employed by the

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THE INVISIBLE ENEMY

enemy, and thus failed to recognize them priorto accidental detonation.

The following illustrations represent someof the devices employed by the VC/NVA inSouth Vietnam.

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THE INVISIBLE ENEMY

VIET CONG CHEMICAL FUZEThis fuze was employed to set off mines and

TNT demolition blocks. It was eight inches longand operated as follows: The tube at the leftcontained a solution of copper sulfate. When itwas broken, the solution soaked the cotton in acontainer that surrounded a release wire. Theresulting chemical reaction eroded the releasewire. The spring forced the firing pin againstthe primer. The primer detonated a fuze thathad a tetryl charge. Delay was between 20 to38 minutes.

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THE INVISIBLE ENEMY

VIET CONG MUDBALL MINEThe mudball mine consisted of a hand

grenade encased in sun-baked mud or clay. Thesafety pin (pull ring) was removed and mudmolded around the grenade. After the muddried it held the lever of the grenade in the safeposition. The mudball was placed on trails oranywhere troops may walk. Stepping on theball broke the dried mud apart and released thelever detonating the grenade. The US M26 andM33 hand grenades were the most commonlyused grenades for this purpose.

SUN BAKED MUD OR CLAYAPPROX. HALF INCH THICK

SAFETY PINREMOVED

GRENADE

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THE INVISIBLE ENEMY

GRENADE IN TIN CAN MINEA tripwire was wrapped around the fuze of

a grenade and then the grenade was placedinside a tin can that held the safety lever inplace. The tin can was then tied securely inplace, the tripwire strung and the safety pinremoved from the grenade. When a victimtripped the wire, the grenade was pulled out ofthe can releasing the safety lever whichdetonated the grenade.

TIN CAN

GRENADE

TRIPWIRE

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THE INVISIBLE ENEMY

TIN CAN ANTI-PERSONNEL MINEThe tin can mine was constructed from

sheet metal or any discarded metal container(C-ration, beer, or soft drink can). The firingdevice for the explosive was an improvised fuzewith zero delay action. A hand grenade fuzecould be used by removing the delay element.The mine functioned by a tripwire attached tothe pull ring. Pressure on the tripwire pulledthe pull ring, activating the mine in the samemanner as a hand grenade.

FUZEBODY

SODACAN

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THE INVISIBLE ENEMY

81mm MORTAR CONTAINER MINEThis mine was constructed of an 81mm mor-

tar shell container with the cap intact and thebottom plugged with a round piece of wood ofthe same diameter, 5/8 inches thick. An electricblasting cap or fiction fuse were utilized withthis mine. In the friction fuse, a brass frictionwire was pulled through a black powdercharge.

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THE INVISIBLE ENEMY

CAST-IRON ANTI-PERSONNELFRAGMENTATION MINE

This locally made cast iron mine resembleda stick hand grenade with a very short handle.The mine body was usually painted grey andhad serrations for fragmentation effect. Theword "MIN" was often found cast into the body.The handle housed a pull-friction igniter. A tugon a tripwire attached to the friction igniterwould activate the fuze. The mine was 2 inchesin diameter and 6 V2 inches long. It weighed 2pounds and contained TNT.

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THE INVISIBLE ENEMY

CHINESE COMMUNIST NO 8 DUAL-PURPOSEMINE

This device had a double-acting fuze. A pres-sure of 30 pounds on the pressure spider or apull of 10 pounds on an attached tripwire woulddetonate the mine. This mine contained fivepounds of explosive, had an overall weight of12 pounds and was 9 inches in diameter by 4inches high. It was made of cast iron and coatedwith creosote for waterproofing.

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THE INVISIBLE ENEMY

BOUNDING FRAGMENTATION MINEThe bounding mine was improvised from

expended US M2 bounding mines or M48tripflare cases. A wooden cylinder slightlysmaller in diameter than the mine case washollowed out so that a standard grenade couldfit inside. The wooden cylinder (with enclosedgrenade) was then fitted into the mine case andthe grenade's safety pin extracted. When themine was detonated the cylinder and grenadewere propelled upward. As the wooden cylinderand grenade separated, the handle flied off thegrenade, activating the fuze.

GRENADE

LEADS TOELECTRICDETONATOR

WOODCYLINDER

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THE INVISIBLE ENEMY

VIET CONG "TOE POPPER" MINEThis mine was fabricated of cartridge cases

or pieces of pipe of various sizes. It was loadedwith a charge of black powder, a primer, and avariety of fragments for missile effect. When avictim stepped on the mine, the igniterdetonated the black powder charge andpropelled the fragments upward.

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THE INVISIBLE ENEMY

CARTRIDGE TRAPFour simple and easily obtainable com-

ponents made up this mine; a bamboo tube, anail, a piece of wood, and any small arms am-munition or M79 round. The piece of wood wasused as a base. The bamboo tube was placedupright on the wooden base and a nail drivenup through the wood to penetrate the bottom ofthe bamboo. The cartridge was then wedgedinto the bamboo so that the primer was touch-ing the point of the nail. Partially buried alonga trail or path, the pressure of a man's footstepping on the nose of the cartridge forced theprimer onto the nail, firing the cartridge.

CAMOUFLAGEDBAMBOO SLAT

CARTRIDGE

BAMBOO

NAIL OR FIRING PIN

WOODEN BOARD

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THE INVISIBLE ENEMY

DIRECTIONAL FRAGMENTATION MINE(DH-10)

Commonly referred to as a "CHICOM orViet Cong claymore," this mine had charac-teristics similar to the US M18A1 ClaymoreMine. Fuzed electrically, it was a command-detonating device designed for employmentfrom ambush or defensive positions. This minewas sometimes fixed on bipods and placed onall types of terrain. Effective range againstpersonnel was over 200 meters and againstthin-skinned vehicles of over 50 meters. Con-structed of a cone shaped piece of steel, it was12 inches in diameter and 2 inches wide. Itweighed 20 pounds. The bipods where com-posed of four steel rods and two frames. Five or

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THE INVISIBLE ENEMY

ten pounds of explosives where placed on oneside while the other side was covered withscrap metal or steel pellets. The explosionpropelled the pellets. The concave side of themine was aimed at the objective so that whenthe mine exploded, fragments would be shot inan arc. Some mines contained from 420 to 450round steel fragments, each 12mm diameter.

A testament to the effectiveness of thesemines was recorded during OPERATIONCEDAR FALLS: An infantry unit quickly formedup after clearing its landing zone. As the pointsquad moved forward from the landing zonetoward its designated blocking position,tragedy struck. Two command-detonatedclaymore mines exploded and two men fell. Alarge boobytrap (probably another claymoremine) mounted in a tree exploded and its frag-ments downed two more men. The squad hadwandered into an enemy minefield. Theplatoon medical corpsman was injured when hestepped on an anti-personnel mine while tryingto aid the wounded.

Another technique where the claymorewere used was around tunnel entrances. When-ever a tunnel was located, a Tunnel Rat squadwould be sent down to clear and explore it. Inmany instances other personnel would gather

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THE INVISIBLE ENEMY

around the tunnel entrance to provide securityor just out of curiosity. The Viet Cong wouldplace claymore mines near the tunnel entranceand upon learning of the Tunnel Rat squadbeing inside the tunnel would detonate themine inflicting casualties on the personnelabove ground.

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THE INVISIBLE ENEMY

POMZ-2 ANTI-PERSONNEL MINEChinese Communist copies of the Soviet

POMZ-2 mine were also employed by theVC/NVA. Weighing only 4.4 pounds, it was easi-ly carried and could be placed quickly. Fuzedfor detonation by tripwire (tension release orpressure release), it could also be rigged electri-cally for command detonation.

BODYPULL WIREINSIDE HERE

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THE INVISIBLE ENEMY

COCONUT MINEThis mine consisted of packing a hollowed-

out coconut with explosives and placing rockson top of it to act as shrapnel.

ROCKS

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THE INVISIBLE ENEMY

BAMBOO MINEA cleaned-out joint section of bamboo was

filled with explosive, scrap metal, and a frictionfuze which was activated by a tripwire.

BAMBOOSECTION

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THE INVISIBLE ENEMY

IMPROVISED INCENDIARY GRENADEThis spherical-shaped grenade was used to

set fire to flammable materials. It was made oftwo hemispherical shaped pieces of metalwelded together. It was 1 1/2 inches in diameterand weighed 1 1/2 ounces. Two small holes in thegrenade were sealed with a piece of light paper.One third of the grenade case was filled withsodium, a substance that will burn and smokeupon contact with water. A coat of wax and thepieces of paper were removed before use. Whenthrown into water, the grenade would send outflames and smoke for 4 to 5 seconds. Despitethe burning, the incendiary grenade caseremained intact and emitted a smell similar tothat of kerosene. If touched, it felt as if it wascovered with a coat of soap.

PAPER

WAX

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THE INVISIBLE ENEMY

IMPROVISED MORTAR HEAD MINEThis mine was a mortar head buried with

the fuze at ground level. When a victim steppedon the fuze the mortar would detonate.

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THE INVISIBLE ENEMY

BICYCLE BOOBYTRAPBicycles were sometimes rigged to serve as

boobytraps by the Viet Cong. The main chargeand electric detonator were held in the uprighttube of the frame under the seat. An electricwire was wound outside the frame to lead to awatch and two 4.5-volt batteries that wereplaced inside the bicycle's headlight. Duringmovement, the ignition device was not linkedto the explosives. Upon arrival at the targetarea, these two components were connected,and the watch preset to donate the charge sometime later.

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THE INVISIBLE ENEMY

FIVE GALLON CAN BOOBYTRAPThis was a homemade boobytrap that func-

tioned by electricity and was detonated by atime delay firing device. The explosive chargewas placed in a US 5-gallon can. A rectangularhole was cut in the bottom with a hinged coverunder which a firing device was placed. Theignition device was composed of two 4.5-voltbatteries and two watches. Duplication madethe device more reliable. The can contained 45pounds of explosives. Two holes were bored onthe center plate and two wires from the ex-plosive went through these holes and were con-nected to two outer plugs. The watches werethen adjusted to explode the mine at aprescribed time. At the prescribed time, thehour hand touched a copper screw inserted intothe watch crystal closing the circuit to theelectric detonator.

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THE INVISIBLE ENEMY

ANTI-PERSONNEL MINEThis mine was constructed of sheet metal

with a dark painted case. It was a modifiedgrenade equipped with one iron or tin lug on itsbody. When the safety ring was pulled out, aspring was released and a firing pin wouldstrike the primer and detonate the mine. Themine was 2 inches in diameter and 6 incheslong. It weighed 2 pounds.

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THE INVISIBLE ENEMY

SOVIET HAND GRENADE, RGD-33The RGD-33 offensive and defensive hand

grenade was a dual-purpose grenade. As anoffensive grenade, it had a 5.5 yard lethalradius. By adding a fragmentation sleeve, itbecame a defensive grenade, which had a 27yard lethal radius. This sheet metal grenadewas normally painted olive brown. The grenadewas 2 inches in diameter and 7 1/2 inches long.It weighed 1 1/2 pounds. The grenade wasthrown vigorously. A spring in the handleforced the body back quickly and the firing pinstruck the primer actuating the delay element.The grenade detonated in 3-4 seconds.

FRAGMENTATIONSLEEVE

THE INVISIBLE ENEMY

SOVIET HAND GRENADE, F-lThe shape and operation of the F-l hand

grenade were similar to those of the US Mk 2grenade. The case was of serrated cast iron andpainted olive drab. The grenade weighed 1 1/2pounds and was 2 1/4 inches in diameter by 5inches long. The effective fragmentation radiuswas 15 yards. When thrown, the safety lever ofthe grenade was released, loosening the springof the firing pin that ignited the primer anddetonated the grenade. Delay time was 3 to 5seconds.

FUZE BODY

DETONATOR

BURSTINGCHARGE

GRENADEBODY

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THE INVISIBLE ENEMY

SOVIET HAND GRENADE, RG-42This anti-personnel grenade had a sheet

metal cylindrical body that contained 100 gmTNT. It was 2 1/4 inches in diameter and 5inches long. It weighed 14 ounces. When thegrenade was thrown, the safety lever wouldspring upward and leave the grenade body. Thefiring pin was forced down and struck theprimer that ignited the time fuze and set off thegrenade. Delay was 3 to 4 seconds.

FUZE BODY

DETONATOR

BURSTINGCHARGE

GRENADEBODY

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THE INVISIBLE ENEMY

VIETNAMESE CIGARETTE LIGHTER PISTOLThis item was actually a firearm that was

probably made for assassination missions. Thebody of the lighter housed a tube containing thefunctional parts. This weapon was primarily ashort range device. The user probably could nothit a man-size target beyond 10 feet.

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THE INVISIBLE ENEMY

FOUNTAIN PEN WEAPONThis weapon had the shape of an ordinary

fountain pen with a fastening clip. It was 5inches long, half inch in diameter, and firedcaliber .22 bullets. The pen body was made of asmooth, thin metal tube and the bore had noriflings. The weapon was employed at shortrange (point-blank to 5 feet). To load, the barrelwas removed and a cartridge inserted. Theoperating handle was pulled to the rear andturned left until it engaged in the safety lock tocock the weapon. When the operating handlewas turned right, it disengaged from the safetylock and by the force of the spring the firing pinwas pushed forward striking the primer andfiring the weapon.

92

Non-ExplosiveBoobytraps

THE IDEA OF non-explosive boobytraps is asold as man. From the simple earth pit linedwith sharpened stakes to highly sophisticatedmechanisms of triggered coils and latches, theViet Cong employed them all. The principleemployed was simply to use anything thatwould catch the victim by surprise.

Amazingly, the Viet Cong used and some-times even trained animals and insects asboobytraps.

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THE INVISIBLE ENEMY

BARBED-SPIKE PLATEThe barbed-spike plate was the basic ele-

ment of all Viet Cong non-explosive boobytraps.The plate, a flat piece of wood or metal, wasused as a base to fasten any number of barbedspikes. The spikes, ranging in length fromseveral inches to several feet, were fastenedsecurely to the base. When a man stepped orfell on the spiked plate, or was struck by one,the spikes would penetrate, producing aserious wound.

THE TOP OF THEBARBED SPIKE PLATE

BOTTOM OFSPIKE WELDED

94

THE INVISIBLE ENEMY

SPIKE TRAP BOXThis device was a simple wooden box made

of boards joined together with four corner posts.The box had a lightweight top but the bottomwas removed. Barbed spikes were placed in theground at the bottom pointing upward. Thistrap was usually set up on dirt roads and trailsto take advantage of favorable camouflage.

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THE INVISIBLE ENEMY

POINTED BAMBOO STAKESMade of bamboo which had been sharpened,

the stakes were stuck in the ground andcovered with grass. When a weapon was firedor a grenade thrown, troops seeking cover wereimpaled.

MINES

M I N E S

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THE INVISIBLE ENEMY

SPIKE TRAP PITA trap pit was a large trap box with a bam-

boo top. Stakes were made of sharpened bam-boo or barbed spikes and used to line the box.When a man stepped on the trap he would fallinto the pit. The top turned on an axle; there-fore, the trap did not need to be reset to workagain. The pit was often prepared as a defen-sive obstacle and then made safe by locking itin place with a crossbeam (so it could be crossedsafely by the enemy) until the desired time ofuse.

CROSSBEAM LOCK

BAMBOO TOP

AXLE

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THE INVISIBLE ENEMY

TRAP BRIDGEA small footbridge was partially cut in the

middle. The cut was then camouflaged withcoverings of mud, grass etc. Barbed spikes orsharpened bamboo stakes were placed underthe cut, using the water, mud or foliage underthe bridge as camouflage. The weight of a manon the bridge would cause it to collapse, tum-bling the victim onto the spikes. Like the spiketrap pit, bridges could be prepared in this man-ner, then braced for normal use. At the ap-proach of American or South Vietnamese forcesthe braces would be removed.

CUT AT THE MIDDLE ANDCOVERED WITH MUD

98

THE INVISIBLE ENEMY

STEEL ARROW TRAPThis trap utilized a bamboo tube (usually

about 3 feet long) as a launcher. A steel arrowwas placed in the tube. Using a block of woodas the bolt, a strip of strong rubber for powerand a catch to lock the rubber strip, the devicewas fired with a tripwire. When the victimtripped the wire, the latch disengaged, allow-ing the rubber strip to launch the arrow.

PIECE OF WOOD

STEEL ARROW RUBBER BAND

TRIPWIRE

99

THE INVISIBLE ENEMY

BAMBOO WHIPA strip of springy bamboo from 3 to 10 feet

in length was used to make a bamboo whip. Abarbed-spike plate was secured to the tip of thebamboo (or several of the spikes driven throughthe bamboo), and the whip was drawn back andsecured. A tripwire was then latched to thewhip and the wire strung across the trail. Whena man tripped the wire, the bamboo wasreleased, and swung around, striking the vic-tim with the spikes.

TRIPWIRE

100

THE INVISIBLE ENEMY

CROSSBOW AND ARROWSimilar to the Steel Arrow Trap, this trap

held an arrow under tension in the bow. A tripwire tied to a release devise released the arrow.

CROSSBOW

ARROW

101

THE INVISIBLE ENEMY

SPIKED MUD BALLBamboo spikes were run through a heavy

mud ball which was suspended from a treeusing vines. Released by a tripwire, the ballswung like a pendulum across the trail or roadstriking its victim.

VINES ORROPE

MUDBALL

SPIKES

102

THE INVISIBLE ENEMY

BEAR TRAPA bear trap was two spiked boards joined at

the ends so they would pivot. The boards wouldpivot upward, when a victim stepped on them,impaling the spikes into the leg above the foot.

WOOD BOARD AXLE

103

THE INVISIBLE ENEMY

SCORPIONSA box full of scorpions was rigged with a

tripwire. When the wire was tripped the boxwould open and release the scorpions.

104

THE INVISIBLE ENEMY

BEES AND HORNETSHives of aggressive bees and hornets were

placed along trails and roads. The hives weresometimes covered with paper that was riggedto a trap on the trail with wire. When the trapwas disturbed, the wire ripped the paperreleasing the bees or hornets.

PAPERWRAPPEDHIVE

TRIPWRES

105

THE INVISIBLE ENEMY

VENOMOUS SNAKESSnakes were tied up using wire or string on

a board or a piece of bamboo in tunnel entran-ces and narrow passages. When the board wastripped the snake came out and bit the victim.

106

THE INVISIBLE ENEMY

DOUBLE-SPIKE CALTROPThis device was one type of caltrop used by

the Viet Cong. It consisted of a board with nailsdriven through it. The pointed ends werebarbed to make removal from the victim moredifficult. The Viet Cong used these devices withas many as seven points from 2 to 12 incheslong. Occasionally, fecal matter or other filthwas smeared on the points to cause infection.

107

THE INVISIBLE ENEMY

DOUBLE-BARBED SPIKEThis was an improved caltrop spike. The

improvement consisted of a second barbpointed in a different direction then that of thefirst. This arrangement made removal moredifficult. In use, a number of these spikes wouldbe driven through a board so as to standupright.

108

Anti-Tank,Vehicle,and Water Mines

MINES EMPLOYED BY the Viet Congagainst wheeled, tracked vehicles and navalships and boats varied from conventionalmines of foreign manufacture to rigged dudsand locally produced explosive devices. All theindustrially produced mines used againstvehicles were of the type fuzed for detonationat from 150 to 400 pounds of pressure. Theywere buried slightly beneath the surface of theground. The Vietnamese communists generallyemployed these mines as designed but variedfusing and positioning so that there was nodefinite pattern.

109

THE INVISIBLE ENEMY

SOVIET ANTI-TANK MINE TMB-2Designed to avoid detection by a mine detec-

tor, this mine was constructed of black or browntar-impregnated cardboard, 11 inches indiameter and 6 inches high. It was usuallygauged for activation by a force of 350 poundsof pressure. Further, it could be waterproofedby the use of wood and plastic sheeting, withoutlosing its non-detection characteristic. It con-tained 11 pounds of explosive and had an over-all weight of 15.4 pounds.

110

THE INVISIBLE ENEMY

CHINESE COMMUNIST NO 4 DUAL-PURPOSEMINE

Intended for employment against bothvehicles and personnel, this mine incorporateda double-acting fuze that could detonate themine under either of two circumstances: thefirst, when a load of 30 pounds of pressure wasapplied to the pressure spider; the second,when a pull of 10 pounds was exerted on atripwire fastened to the fuze's striker-retainerpin. Constructed of creosoted metal, it carried4 pounds of explosive and had an overall weightof about 10 pounds.

i l l

THE INVISIBLE ENEMY

VIET CONG ANTI-TANK MINEThe Viet Cong locally constructed anti-tank

mines with iron case consisting of two parts, acap or pressure plate and a body. Two holeswere located in the top of the mine, one toaccommodate the fuze and the other to load theexplosive (TNT). The mine was 8 inches indiameter and 3 inches high. It weighed 11.5pounds.

112

THE INVISIBLE ENEMY

CONCRETE FRAGMENTATION MINEThis mine was constructed of explosive en-

cased in a cylindrically shaped concrete shellwith a flat side for stable emplacement. A 2-inch diameter pipe on one end of the mineserved as a carrying handle and detonatorhousing. The two swivels on top of the minewere used to tie it to an object. Usuallyemployed as a command-detonating mine, itwas equipped with an electrical firing device.The mine was 7 inches wide and 22 inches long.It weighed 13 pounds and contained TNT.

113

THE INVISIBLE ENEMY

NVA CAST-IRON FRAGMENTATIONANTI-TANK MINE

Produced in North Vietnam, this egg-shaped mine was made of cast-iron with serra-tions on its outer surface. On the mine body andbetween the ends was a handle that was passedthrough two eye hooks attached to the minebody. There was a hole, 2 inches in diameter,with a cover at one end of the mine. When usedthis cover was removed and replaced by anelectric blasting cap for command detonation.This mine was 5 inches in diameter, 9 incheslong and weighed 12 pounds.

114

THE INVISIBLE ENEMY

VIET CONG MOUND-SHAPED MINEManufactured locally in Viet Cong mine fac-

tories, this mine contained an iron-pipedetonator encased in concrete. There were twoiron swivels on the mine body to tie it to anobject. Another command-detonating mine, itwas fuzed electrically. The mine was 12 incheslong, 5 3/4 inches wide, and 6 inches high. Itcontained TNT and weighed 13 pounds.

DETONATORLEAD

115

THE INVISIBLE ENEMY

VIET CONG ROUND VOLUME MINEProduced locally in Viet Cong mine fac-

tories, this mine was a prototype of numerousother Viet Cong-manufactured explosivedevices. Constructed of sheet metal, withwelded seams, it generally weighed about 15pounds, of which 13 pounds were explosive. Themine was 5 inches in diameter and 17 incheslong. Command detonated, it was fuzed electri-cally and employed two detonators, one in eachend of the mine. The same principle of construc-tion was applied to salvaged artillery shellcasings, expended LAAW launchers, and mostother devices using metal containers.

DETONATOR

DETONATORLEAD

116

THE INVISIBLE ENEMY

VIET CONG BOX MINE AND DEMOLITIONS

The Viet Cong box mine was constructed ofwood utilizing discarded ammunition boxes orany scrap material. Mine detectors could notlocate these devices. They could bewaterproofed with plastic sheeting. Box mineswere produced in various sizes but the mostcommon contained about 40 pounds of ex-plosive. The mine could be fuzed for commanddetonation or self-detonation by the use ofvarious devices. The explosive charge wasusually made up of standard Soviet or ChineseCommunist 1-pound demolition blocks. TheSoviet TNT demolition block was rectangular

117

THE INVISIBLE ENEMY

shaped and had a 1/4 inch diameter hole in theend of the block. Its size was 2 by 2 by 4 inchesand weighed 3/4 pound. It was covered with waxpaper that had an inscription in Russian as tothe contents. This demolition block was used asa booster block for all demolition work. TheChinese Communist TNT demolition block wasrectangular in shape, yellowish in color,wrapped in oil paper with Chinese markings onthe outside meaning: TNT Demolition block,200 grams. It was 1 by 2 by 4 inches in size andweighed half pound.

118

THE INVISIBLE ENEMY

B-40 ANTI-TANK BOOBYTRAPA length of bamboo was placed at an angle

of 45 degrees along the shoulder of the road. AB-40 rocket was then placed in the bamboo tubeand fired electrically by command detonationas the tank or vehicle crossed the line of fire.

RPG ROUND

BOOSTER —

119

THE INVISIBLE ENEMY

SOVIET ANTI-TANK MINE TM-41Constructed of blued steel, sometimes

painted olive drab or white, the TM-41 carriedan explosive charge of 8 pounds and had a totalweight of 12 pounds. It was 10 inches indiameter and 5 inches high. A force of 350pounds of pressure on the lid would activate thefiring device. With very little additionalwaterproofing it could remain operational in-definitely.

120

THE INVISIBLE ENEMY

CHINESE COMMUNIST Ml Al ANTI-TANKMINE

Manufactured in Communist China and lo-cally, this mine was similar to and often mis-taken for a US pre-World War II mine. Made ofmetal, it was painted olive drab with the yellowmarkings "MINE M1A1-TNT". Two holes werelocated in the top of the mine, one to accom-modate the fuze and the other to load the ex-plosive, usually TNT. It was activated by 200pounds of pressure on the pressure plate. Thismine contained 4 pounds of explosive andweighed 11.5 pounds. It was 8 inches indiameter and 3 inches high.

121

THE INVISIBLE ENEMY

VIET CONG IMPROVISED SHAPED CHARGEMINE

This homemade shaped charge had threelegs to serve as stand-off. The explosive chargecontainer was constructed of black sheet metal,rolled and hermetically welded. It was 9 inchesin diameter, 11 inches high and weighed 21pounds. The charge contained 13 Vi pounds ofTNT that was ignited electrically.

122

THE INVISIBLE ENEMY

VIET CONG RIVETED SHAPED CHARGEThis short pyramidal shaped charge func-

tioned by electricity and was constructed ofrolled black sheet metal that was fastenedtogether by rivets. It stood 8.5 inches high andweighed 17.5 pounds. The charge contained 11pounds of Melinite explosive.

123

THE INVISIBLE ENEMY

VIET CONG MORTAR SHELL MINEThis mine was a modified British 100mm

mortar shell (oval-shaped case) utilizing anelectric firing device. The fuze well was cut offand a hole was drilled into the explosive toaccommodate an electric blasting cap. The shellwas made of cast iron, 4 inches in diameter and15 inches long. It weighed 13 pounds and con-tained 3 V2 pounds of TNT.

124

THE INVISIBLE ENEMY

VIET CONG BOX-SHAPED MINEThis mine was constructed of cement with

an electric firing device and serrations in thecenter of the case. The end of the mine had apiece of iron attached by four bolts to hold theelectric blasting cap. The mine was 8 inches indiameter and 8 inches high. It weighed 13pounds and contained TNT.

126

THE INVISIBLE ENEMY

VIET CONG TURTLE-SHAPED MINEThis mine was constructed of cement with

an electric firing device. Usually the mine wasfastened to a long pole. Apart of the case had asquare piece of iron attached by four screws tohold the fuze in place. The mine was 5 inchesin diameter and 9 inches long. It weighed 13pounds and contained TNT.

126

THE INVISIBLE ENEMY

VIET CONG HOLLOW CONE MINEThis mine was cone shaped and made of

sheet metal held together with rivets. It wasequipped with two pressure-pull ignitingdevices that detonated the mine in 9 seconds.The mine was 9 inches in diameter and 8 incheshigh. It weighed 15 pounds. The igniting devicewas locally made. It consisted of a Caltex oil canthat contained two detonators, placed in paral-lel lines in the mine. The components of themine were two pressure-pull strings, two ignit-ing devices, two igniter charges, and twodetonators.

127

THE INVISIBLE ENEMY

VIET CONG SHORT CONE-SHAPED MINEThe Viet Cong locally made short cone-

shaped mine weighing 27 pounds and contain-ing 15 pounds of TNT. The outer case was madeof sheet iron and the upper part had two holesthrough which two electric blasting caps wereintroduced to increase reliability. The mine hada bell-shaped base, 11 inches in diameter. Ahandle was attached to the side of the mine caseby two rivets.

128

THE INVISIBLE ENEMY

VIET CONG WATER MINEThe Viet Cong homemade water mine was

constructed in shape of a short cone and fabri-cated from sheet metal held together by rivets.The mine was usually painted black andmarked with the number 4 at three differentspots on its outer case. It was 11 inches indiameter and 12 inches high. It weighed 27pounds and contained TNT. The mine was con-structed in different sizes and was operated byelectricity. It was employed to attack navalships and boats.

129

130

BOOSTER

MAIN CHARGE

CARRYINGHANDLE

DETONATOR

HANDLE

THE INVISIBLE ENEMY

VIET CONG TURTLE MINEThis locally constructed mine was made of

separate pieces of black sheet metal fastenedtogether with rivets. There were four U-shapedsupports placed across the bottom of the mine.The mine was 9 inches wide and 5 1/2 incheshigh. It weighed 20 pounds and contained 7 1/2pounds of explosive.

131

THE INVISIBLE ENEMY

SOVIET HAND GRENADE, RPG-40This grenade was used mainly against light

armored vehicles. It was made of sheet metaland contained TNT. It was 3 1/2 inches indiameter and 8 inches long. It weighed 2 3/4pounds. The effective fragmentation radiuswas 22 yards. A detonator was inserted into thegrenade before the grenade was thrown. Theigniting device was placed inside the handlethat was tightly screwed into the top of thegrenade. When the safety pin was removed andthe safety lever released, the grenade was inthe armed position. It fired on impact withoutdelay.

132

THE INVISIBLE ENEMY

SOVIET PARACHUTE HAND GRENADE,SHAPED CHARGE

The parachute stabilized the grenade inflight. It exploded at a low impact angle andhad approximately the same effect as a HEAT(High Explosive Anti-Tank) round. It couldpenetrate 5 inches of steel. The grenade wasmade of tin and was cylindrical in shape. Thecharge was cast TNT. Overall length was 15inches and weighed 2 1/2 pounds. The grenadewas made up of three separate components:body, fuze, and handle. The handle, 2 inches indiameter, contained firing pin, safety pin, andthe parachute. The body, 3 inches in diameter,contained the shaped charge. When thrown,the spring ejected a parachute holding cap atthe head of the handle to the rear and a recoilspring ejected the parachute out of the handle.Upon impact, the inertia-activated firing pinmoved forward, striking the detonator, andfired the grenade.

DETONATOR

HANDLE BODY

133

THE INVISIBLE ENEMY

VIET CONG PARACHUTE HAND GRENADE,SHAPED CHARGE

This grenade was used against tanks andarmored personal carriers. The parachute sta-bilized the grenade and assured proper impactangle at the target. It pierced up to 4 inches ofsteel. The grenade was made of sheet iron witha wooden handle and the charge was cast TNT.Overall length was 13 1/2 inches and weighed1 1/2 pounds. The grenade was made up of fourparts: handle, conical sleeve, body, and war-head. The cone housed the firing pin, safety pin,and parachute. The body, 3 inches in diameter,contained a detonator and the shaped chargewhile the warhead provided the stand-off.When thrown, a spring pulled the parachutecone to the rear and the parachute deployed. Atthe same time, the safety pin was pulled out ofthe grenade. Upon impact, the firing pin struckthe detonator and exploded the grenade.

SLIDING CONICAL WARHEADSLEEVE

REAR SECTIONOF HANDLE

134

THE INVISIBLE ENEMY

SOVIET HAND GRENADE, RPG-6This shaped charge anti-tank grenade was

also used against personnel because of its effec-tive fragmentation radius of 22 yards. It was13 1/2 inches long and weighed 2 1/2 pounds.When thrown, the grenade was balanced byfour pieces of parachute cloth that ejected fromthe handle as the safety lever ejected. Thegrenade exploded on impact. Unlike othergrenades, this type had a crescent shaped headand its handle was made of sheet metal insteadof wood.

CONE CAVITY LINER

BURSTING CHARGE

DETONATOR BOOSTERASSEMBLY

FIRING PIN ANDSPRING

STABILIZING CLOTH

135

THE INVISIBLE ENEMY

SOVIET HAND GRENADE, RPG-43This anti-tank grenade could penetrate up

to 3 inches of steel. It was 12 inches long andweighed 2 3/4 pounds. The grenade stabilizingdevice consisted of two pieces of cloth and asteel cone. The grenade exploded upon strikingthe target.

STABILIZING CLOTH

DETONATOR BOOSTERASSEMBLY

BURSTING CHARGE

FIRING PIN ANDSPRING

CONE CAVITY LINER

136

Anti-HelicopterMining

THE DEGREE OF success that the employ-ment of helicopters had on restricting and con-taining VC/NVA activities was evidenced by theenemy's efforts to destroy or neutralize thesemachines. In addition to intense ground fire,the Viet Cong devised numerous helicopterlanding zone destruction systems. Suchdestruction systems ranged from the primitiveplanting of long pointed stakes to imaginativeexplosive devices. Because of its design, thehelicopter is extremely vulnerable to thesedevices, particularly the rotors and airframe.

In an effort to minimize the threat of "hot"and mined landing zones, US forces developedseveral methods of creating or rapidly expand-

137

THE INVISIBLE ENEMY

ing new landing zones. In a joint Army and AirForce effort, the "combat trap" was developedafter experimentation. The M121 was a 10,000-pound bomb that was parachuted from a fixed-wing aircraft or helicopter over the desiredlanding zone site and detonated at a height thatwould clear away the dense foliage but notcreate a crater in the earth. After the combattrap had finished its job, a construction partyand equipment were taken by helicopter to thenew landing zone to expand it to the desired size.

Special construction equipment weredeveloped for helicopter transport. Equipmentthat could be moved into forward areas byhelicopter included roadgraders, bulldozers,scoop loaders, and many others, each of whichwere sectioned and lifted into the landing zonein two loads, and then assembled for operation.

The following is a description of a trap usedin landing zones during OPERATION JUNC-TION CITY. As the three lifts of chopperstouched down, five heavy command-detonatedcharges were set off by the Viet Cong in the tinyclearing. Three helicopters were destroyed and6 more damaged with a toll of fifteen US soldierkilled and twenty eight wounded. A Viet CongClaymore-type mine was also detonatedwounding five infantrymen.

138

THE INVISIBLE ENEMY

On the following day Rangers discoveredbatteries and a wire in the wood line nearanother landing zone. Following the wire, theyfound four holes filled with explosives. Therewas a center hole, and radiating from it waswire leading to three other holes at a distanceof about twenty-five meters. In each hole werethe necessary detonating caps. In the centerhole were also the following rounds: eight75mm, seven 81mm, fourteen 60mm, and 105pounds of TNT. The other holes had similar butsmaller loads: only thirty-five pounds of TNTeach and various numbers and types of USordnance. It was all set to be command-detonated.

From then on some Army units, when theyplaced artillery and air strike preparatory firesaround and into any landing zone into which itwas bringing troops, always used a number ofinstantaneous fuzed bombs to strike theplanned landing site of its chopper lifts in orderto cut any wires and yet not chew up the terrainso much that it would be difficult to land andtraverse.

139

THE INVISIBLE ENEMY

HELICOPTER EXPLOSIVE TRAPSGrenades, artillery/mortar rounds, or any

other type of exploding ordnance were mountedin trees or on the surface of the landing zone.The explosive devices were rigged for tripwiredetonation and the wire strung to looselyplaced poles. The rotorwash of landing helicop-ters would blow the poles from their loose posi-tion, tripping the device.

140

THE INVISIBLE ENEMY

HELICOPTER EXPLOSIVE TRAPSA 13-year-old Vietnamese boy once claimed

that the Viet Cong had forced him to recon-noiter helicopter landing zones. The boy wasinstructed by the Viet Cong to place handgrenades in the zones with strings wrappedaround the levers, pieces of paper attached tothe free ends of the strings and the rings (pullrings) pulled. Rotorwash from landing helicop-ters would then blow the paper, unwrap thestring, and release the safety lever.

141

Index

AH-1G gunship, 34Arrow markers, 49-51Artillery

Artillery Ambush, 28H&I (harassment and interdic-

tion), 28B

B-40 AT boobytrap, 119Bamboo marker, 53Bamboo mine, 82Bamboo rectangle marker, 52Bamboo tripod marker, 54Bamboo whip, 100Banana leaf marker, 56Barbed spike plate, 94Bear trap, 103Bees and hornets trap, 105Bicycle mine, 85Boobytraps, Non-explosive

Bamboo whip, 100Barbed spike plate, 94Bear trap, 103Bees and hornets trap, 105Crossbow and arrow trap, 101Double barbed spike, 108Double spike caltrop, 107Pointed bamboo stakes, 96Scorpions trap, 104Spike trap box, 95Spike trap pit, 97Spiked mud ball, 102Steel arrow trap, 99Trap bridge, 98Venomous snakes trap, 106

Bounding fragmentation mine, 74Box shaped mine, 125British 100mm mortar shell, 124Broken bush or stick marker, 55

cCartridge trap mine, 76Cast iron fragmentation AT mine,

114Cast-iron fragmentation mine, 72Chemical fuze, 67Chieu Hoi, 30

Chinese Communist M1A1 ATmine, 121

Chinese Communist No. 4 mine,111

Chinese Communist No. 8 mine, 73Cigarette lighter pistol, 91Coconut mine, 81Combined Material Exploitation

Center, 15Mobility Section, 16

Concrete fragmentation mine, 113Crossbow and arrow trap, 101CS Grenade (tear gas), 18

DDemolitions

Chinese Communist, 118Soviet, 117

Directional Fragmentation mine(DH-10), 77

Double barbed spike, 108Double spike caltrop, 107Duds, 9 -10, 20, 22, 109

E81mm mortar container mine, 71ENSURE 202 Tank-Mounted Ex-

pendable Mine Roller, 41F

5th Special Forces Group's ProjectDelta, 25

Five gallon can mine, 86Forked stick marker, 60Fountain pen weapon, 92

GGrenades

CS Grenade (tear gas), 18Grenade in tin can mine, 69HC Smoke Grenade, 18Improvised Incendiary Grenade, 83M26 Grenade, 21, 42, 44 - 45, 68M33 Grenade, 68Mk 2 grenade, 89Soviet grenade, F-l, 89Soviet grenade, RG-42, 90Soviet grenade, RGD-33, 88Soviet grenade, RPG-40, 132Soviet grenade, RPG-43, 136

142

Grenades (continued)Soviet grenade, RPG-6,135Soviet parachute grenade, shaped

charge, 133VC parachute grenade, shaped

charge, 134Growing grass marker, 58

HHC Smoke Grenade, 18Helicopter explosive trap, 140 -141Helicopter Illumination System

(Lightning Bug-Firefly), 33Herbicides

Agent Blue, 31 - 32Agent Orange, 31

Hoi Chanhs, 18Hollow cone mine, 127

IIncendiary Grenade, Improvised, 83

KKit Carson Scouts, 30

LLong Range Patrols (LRP), 25LVTE

Linecharge, 40Mine Excavator, 40

MM106 Riot Control Agent Dis-

penser (Mity Mite), 18M121 "Combat trap" 10,000-pound

bomb, 138M14 rifle, 26M18A1 Claymore mine, 77M2 bounding mine, 74M26 Grenade, 21, 42, 44 - 45, 68M33 Grenade, 68M48 tripflare case, 74M79 "blooper" round, 76Mine detectors, 38 - 39, 43Mine indicators

Arrow markers, 49-51Bamboo marker, 53Bamboo rectangle marker, 52Bamboo tripod marker, 54Banana leaf marker, 56Broken bush or stick marker, 55Forked stick marker, 60Growing grass marker, 58

Parallel stick marker, 57Rock markers, 61Spaced stick marker, 62Stakes with X marker, 64Track markers, 63Trail markers, 59

Minefields, 8, 78Mines

81mm mortar container mine, 71B-40 AT boobytrap, 119Bamboo mine, 82Bicycle mine, 85Bounding fragmentation mine, 74Box shaped mine, 125Cartridge trap mine, 76Cast iron fragmentation AT mine,

114Cast-iron fragmentation mine, 72Chinese Communist M1A1 AT

mine, 121Chinese Communist No. 4 mine,

111Chinese Communist No. 8 mine,Coconut mine, 81Concrete fragmentation mine,Directional Fragmentation mine

(DH-10), 77Factories, 9,11 -12,18 - 19, 25,

115 -116Five gallon can mine, 86Grenade in tin can mine, 69Hollow cone mine, 127Improvised mortar head mine, 84M18A1 Claymore mine, 77M2 bounding mine, 74Modified grenade mine, 87Mortar shell mine, 124Mound shaped mine, 115Mudball mine, 68POMZ-2 mine, 80Riveted shaped charge mine, 123Round volume mine, 116Shaped charge mine, Improvised,

122Short cone shaped mine, 128Soviet AT mine, TM-41,120Soviet AT mine, TMB-2, 110Tin can mine, 70"Toe Popper" mine, 75Turtle mine, 131

143

Mines (continued)Turtle shaped mine, 126Two-part water mine, 130VC AT mine, 112Water mine, 129

Mity Mite, 18Mk 2 grenade, 89Modified grenade mine, 87Mortar head mine, Improvised, 84Mortar shell mine, 124Mound shaped mine, 115Mudball mine, 68

NNuisance mining, 8

oOPERATION CEDAR FALLS, 78OPERATION JUNCTION CITY, 138OV-1C Mohawk helicopter, 33

PParallel stick marker, 57"Pink light" infrared searchlight, 26Pointed bamboo stakes, 96Police Field Force, 27POMZ-2 mine, 80

RRadar, 23, 34

AN/PPS-4, 23AN/PPS-5, 23

Riveted shaped charge mine, 123Rock markers, 61Rome K/G Clearing Blade - Rome

plow, 30Round volume mine, 116

sScorpions trap, 104Scout Dogs, 27, 32Sensors, 23 - 25, 34 - 35

Acoustic, 24Electromagnetic, 24Magnetic, 24Seismic, 24

Shaped charge mine, Improvised,122

Short cone shaped mine, 128Small unit cordon and search

operations, 27Sniper, 25 - 27Sniper Scope, 26

Soviet AT mine, TM-41,120Soviet grenade, F-l, 89Soviet grenade, RG-42, 90Soviet grenade, RGD-33, 88Soviet grenade, RPG-40, 132Soviet grenade, RPG-43, 136Soviet grenade, RPG-6, 135Soviet parachute grenade, shaped

charge, 133Spaced stick marker, 62Spike trap box, 95Spike trap pit, 97Spiked mud ball, 102Stakes with X marker, 64Starlight scope, 26 - 27Steel arrow trap, 99

TThunder run" technique, 30Tin can mine, 70Toe Popper" mine, 75Track markers, 63Trail markers, 59Trap bridge, 98Tunnel, 11 - 14, 18 - 19, 26, 78 - 79,

106Tunnel Rat, 18, 78 - 79Turtle mine, 131Turtle shaped mine, 126Two-part water mine, 130

uUH-ID/H Nighthawk helicopter,

33-34US forces, 7 - 12, 14 - 17, 22 - 23,

42, 65, 98,137 -138US Marines, 7

VVC AT mine, 112VC claymore mine

See: Directional fragmentationmine (DH-10)

VC parachute grenade, shapedcharge, 134

Venomous snakes trap, 106VIP (Volunteer Informant Pro-

gram), 22

wWater mine, 129

144

Closely examines the use of minesand boobytraps as an effectiveweapons system, and details howsome of the devices were constructed.

This book, with more than 80 illustrations,captures the ingenuity and extraordinary variety ofthe Viet Cong's most feared weapons: mines andboobytraps.

During the early days of the Vietnam warapproximately 65 to 75 percent of all US casualtieswere caused by mines and boobytraps, many of themimprovised from easily obtained items discarded byAmerican troops.

Here, for the first time, is a book that closelyexamines the use of mines and boobytraps as aneffective weapons system, and details how some ofthe devices were constructed. Topics coveredinclude: mine warfare, enemy sources of supply, VCmine factories, counter-measures, mine indicators,explosive anti-personnel devices, non-explosiveboobytraps, anti-tank and vehicle mines, andanti-helicopter boobytraps. Must reading for anyoneconcerned with improvised weaponry and boobytraps!