Supporting Arms Employment at Lang Vei

The old Special Forces camp at Lang Vei (XD 795362) was inspected to determine the extent of damage inflicted by US ordnance on the fortifications there. The camp lay astride Route 9, approximately 500 meters east of the new camp (XD 784357). When entered on 23 April, the camp was mostly rubble, having been subjected to a heavy bombardment during most of February and March. At least one B-52 strike had been employed across a portion of the camp causing widespread damage to the bunkers and had completely obliterated the evidence of previously existing fortifications.

The fortifications in the camp were well constructed from steel engineer stakes, sandbags, reinforced concrete and heavy timber. They offered a higher silhouette than the NVA bunkers and were therefore more vulnerable to the effects of artillery and air ordnance. Each blockhouse (French origin) measured 6 feet per side, and consisted of 12 inches of reinforced concrete (Figure 17). The roof was constructed of 4 inch I-beams spaced 12 inches apart which supported a 12 inch concrete slab overhead. Bunkers and other fortifications were interconnected by a trench which circled the outer perimeter of the camp. Living and fighting bunkers were supported by large logs and timbers, and extensive sandbagging had been used (Figure 18). These bunkers held from 3 to 5 men, were 70 percent underground, and had fighting apertures facing the perimeter and the sides. These bunkers hold up remarkably well under the heavy bombardment.

Artillery had heavily damaged much of the equipment and large structures above ground, but was generally ineffective against the lower silhouetted bunkers along the perimeter. The most recent clearing operation had destroyed much of the evidence of supporting arms against the NVA in the camp. No evidence of napalm was found. It was clear that in order to destroy a bunker of this type a bomb had to hit the bunker, penetrate it, and explode on the inside. In many cases, it was apparent that the blast effect of near misses was cushioned by the soft laterite soil, causing minor damage to portions of the sandbags and leaving only a large crater. The effect of the bombs was similar to the heaving effect of the standard cratering charge. Debris was scattered over a wide area, but there was little fragment damage.

Bunkers outside of the crater itself were intact. Concussion damage was more likely to have been severe, but its effects were unknown. The area afforded an excellent target for air and artillery. Observation was excellent, and the camp was approachable from three directions. Artillery fire from Khe Sanh was extremely accurate, and there was considerable fragment damage to the exterior surface of the bunkers. The ordnance had not penetrated the bunkers or other fortified structures.

Of special interest were the bunker and adjacent craters shown in Figure 19. The bunker was of US construction and consisted of an 8x8x8 feet reinforced concrete 'box' dug completely underground with 2 feet of overhead cover. The only entrance was a 28 inch culvert leading directly into the bunker from the top. Immediately adjacent to the bunker was a bomb crater 38 feet in diameter and 18 feet deep. The distance from the center of the bunker to the center of the crater was 28 feet. No damage to any portion of the bunker was found. There was no fracturing of the 10 inch walls on the inside, and no fragment damage to the entrance.

Employment of Riot Control Tear Agent (CS)

On three occasions non-persistent CS was employed in an attempt to flush out or interdict enemy movement along major infiltration and supply routes leading to Khe Sanh. In each case the method of employment consisted of 3 visually controlled A4 aircraft, each carrying 4 MK20 smoke tanks which ignited on release, dispensing a vapor.

The first employment was on 3 February in the area along the river from XD 803470 to XD 808463. The aircraft were directed by a forward air controller (FAC). Each aircraft made 2 passes and dropped 2 tanks per pass. Area coverage was 30 percent. Poor flying weather had prohibited early morning employment during optimum atmospheric conditions. Delivery time was 1500, when a lapse condition existed. Most of the vapor dissipated rapidly into the air even though the agent was delivered from altitudes of less than 100 feet. F4 aircraft with napalm and 500 lb high drag bombs were employed approximately 5 minutes after the agent had been delivered, in an attempt to destroy enemy troops as they evaded the effects of the gas and sought shelter elsewhere. However, no troops were observed leaving the area, and the follow-up airstrikes were directed to likely staging/living areas within the target box.

Although no killed by air (KBA) were observed upon completion of the strike, subsequent sensor reports that evening confirmed that the usual infiltration route had changed considerably to avoid the area where the CS was employed. Nonetheless, after 24 hours, infiltration down the streambed had returned to normal. A more persistent CS powder, unavailable at the time, would have been more desirable.

On 5 February a similar method was used to interdict enemy troop movements and destroy troops observed along the streambed in the area bounded by XD 702469 - 714465 - 713462 - 702466. Poor weather again prevented employment until 1430 hours, and the same effects were observed. Aircraft heading was parallel to the stream, approximately 1/4 of the way up the slope on either side. Subsequent airstrikes employing napalm, 500 lb high drag bombs and 5 inch Zuni rockets yielded two secondary explosions at XD 708464. The strike was not successful in interdicting troop movement. Sensor reports indicated the usual movement that night.

On 6 February, a third strike was placed at XD 811467, in the vicinity of a heavily used trail junction. The CS again billowed and was virtually ineffective. Aircraft with 500 and 2000 lb bombs were directed against NVA bunkers and tunnel complexes on Hill 516 (XD 799460). The use of CS as a method of interdicting troop infiltration could be very effective if employed under the following conditions:

• In the early morning, cool clear weather, relatively light winds and neutral or inversion atmospheric conditions
• When a persistent/powdered agent was made available for interdiction
• A vapor agent was made available for flushing the enemy from bunkers, trenches and fighting holes
• Employment was followed by immediate artillery/airstrikes employing VT/Firecracker/CBU antipersonnel munitions, napalm or extended fuze bombs ('daisy cutters')

It was also proven through interrogation and recovery of captured equipment that NVA troops at Khe Sanh were equipped with Soviet PK-1 (Chinese Type 66) Gas Masks. The mask consisted of two pieces, an oral-nasal respirator and a set of goggles. The mask was found to be effective in a CS environment but tended to crack and become useless after exposure to moisture for any prolonged period.

There were no bunker complexes inspected that would have withstood the coordinated use of a CS munition. The living bunkers, although several feet underground., were nevertheless vulnerable to a settling type vapor through either the main entrance off the trenchline, or the air vent located on the side opposite the entrance. After allowing for the gas to permeate the living bunker, follow-up aircraft with CBU type ordnance could provide the rapid area coverage necessary to exploit the effects of the agent.

Use of Napalm in High Grass

There was a tendency to overestimate the effects of napalm as a method of burning off dense elephant grass. It was found that only the area within a 50 foot diameter of the point of impact was sufficiently burned to provide tactical fields of fire, or observation of the ground. In uphill terrain the splashing was retarded and in areas where the terrain sloped away from the aircraft heading, the tendency was to overshoot the desired point of impact. In most cases the grass beyond the 50 foot circle was blackened only at the roots, while the tops remained green. Heavy early morning fog and occasional light rain kept most of the foliage damp which lessened the effects of the napalm.

The heat and suffocating effect of napalm were very effective against personnel in bunkers when it was delivered on the living bunker. Coordinated napalm air 'slams' against the living bunkers, followed by VT/CBU ordnance against exposed troops, were excellent methods of destroying the living areas and enemy assault troops.