Uncle Ho’s Hideout #10 – US Interdiction Against Trail

mpaign Series Vietnam | Uncle Hos Hideout

In Uncle Ho's Hideout series, David Galster shares some of his tips and techniques in scenario research and design for CS: Vietnam.

Dear Compatriots,

Did you know that there was yet another name for the Ho Chi Minh Trail? Indeed, the MACV nicknamed it "Sullivan's Freeway." This issue reveals why, and provides an overview of the vast trail interdiction efforts by the US.

Command Structure

Sorry for all the acronyms, comrades, but you can't discuss the US Military without them. The highest command dealing with the Vietnam War was the Pacific Command, (PACOM). Its Commander in Chief, (CINCPAC), was Adm. Harry D. Felt, in Honolulu. Admiral Ulysses S. Grant Sharp, succeeded him in 1964. Admiral Sharp was deeply involved with many decisions involving the trail.

Three commands under Pacific Command were: US Navy Pacific Fleet, (PACFLT,) Pacific Air Forces, (PACAF,) and US Army, Pacific. (USARPAC)

PACFLT was headed by Admiral Thomas H. Moorer. A sub-component, 7th Fleet was commanded by Vice Adm. William A. Schoech. Carrier Task Force 77, (CTF 77,) provided many jet fighter-bombers.

PACAF was led by Gen. Hunter Harris. Subordinate commands were Thirteenth Air Force at Clark Air Force Base, Philippines, to 2d Air Division, (2nd ADVON,) an arrangement that remained in effect until April 1, 1966, when the 2d Air Division became Seventh Air Force, and was assigned directly to PACAF. Maj. Gen. Joseph H. Moore commanded 2d Air Division. Lt. Gen. William W. Momyer took over Seventh Air Force at its creation.

The key command under USARPAC was the US Military Assistance Command, Vietnam. (MACV)  Gen. William C. Westmoreland commanded MACV, and wanted maximum efforts to stop infiltration.

The main US Cabinet members involved in this saga were Secretary of Defense, Robert McNamara and Secretary of State, Dean Rusk. The Ambassador to Laos played a very big role, since the trail went mostly through Laos. In the early years, Leonard Unger was the Ambassador, but in November 1964, William H. Sullivan succeeded him. As we will see, Sullivan was a strong voice of restraint for all aerial operation aspects. His Air Attache, (AIRA,) was Col. Robert L. F. Tyrrell.

The Laotian Government was led by Prime Minister Souvanna Phouma. The Royal Laotian Air Force, (RLAF) was commanded by General Thao Ma. These leaders' approval and participation was critical.

Early Aerial Reconnaissance

After the 1962 Geneva Neutrality treaty for Laos, reconnaissance flights were suspended. But, in 1963, Secretary McNamara  went to Saigon to review the overall situation and report back to President Johnson. One of his recommendations was to begin mapping the Laos-Cambodia-South

Vietnam borders to obtain data on infiltration routes. High-flying U-2 reconnaissance planes were assigned the aerial photography task.

In early 1964, Operation "Lucky Dragon" began with three U-2 planes from the 4080th Strategic Wing. They were based at the Bien Hoa airbase, and the film was processed at a lab at Tan Son Nhut airfield in South Vietnam.

The evidence for Communist infiltration into South Vietnam continued to accumulate with reports of newer weapons for the Viet Cong such as 75-mm recoilless rifles, heavy machine guns, 90-mm rocket launchers, and large caches of ammunition. There had also been some combat in Laos involving the Pathet Lao, which prompted efforts to provide the RLAF with T-28 aircraft. Another crisis was the junta led by Gen. Nguyen Khanh in South Vietnam.

After conferring with the Joint Chiefs of Staff, (JCS) including Air Force General Curtis LeMay, Secretary McNamara made further recommendations, one of which was to temporarily resume tactical aerial reconnaissance. This came only after obtaining Souvanna Phouma’s consent and acquiescence of Ambassador Unger, who agonized constantly over the international consequences of losing American airmen in Laos.

Operation "Yankee Team" began in May 1964. Admiral Felt ordered low altitude surveillance of specified infiltration routes leading from North Vietnam through Laos into South Vietnam, and against the Ban Thay complex east of Muong Phine. General Moore of 2d Division managed the operation. Four "Able Mable"  RF-101 aircraft from the 15th Tactical Reconnaissance Squadron immediately began flights from Tan Son Nhut Airfield. These would be later supplemented by Navy RF-8A aircraft, flown from the USS Kitty Hawk.

The RF-101C "Voodoo" had began service in 1957 as a reconnaissance jet. The twin turbojet engines provided power for a maximum speed of Mach 1.72. (1825 km/hr) It was used at low and medium altitudes. Six cameras took the place of radar and cannons in the reshaped nose, but it retained bombing ability.

The cameras had longer focal lengths for good photography at 15000 ft, (4570 m) but, cloud cover often forced them to use other cameras at lower altitudes. In some areas of Laos, Communist anti-aircraft guns were effective to 5000 ft. (1520 m)

On 6 June 6 1964, Communist anti-aircraft fire downed a Navy RF-8A near Xiengkhouang, Laos. The pilot, Lt. Charles F. Klusmann, was captured. President Johnson, with Prime Minister Souvanna’s approval, quickly ordered fighter escorts, and authorized return fire. Eight F-100 Super Sabres of the 510th Tactical Fighter Squadron (TFS) were deployed as escorts. They dropped two 750-lb bombs, and fired fifty-seven 2.75-inch rockets on NVA forces near Xiengkhaoung.

As more sorties were completed, considerable photography was turned over to the RLAF to assist its T-28 close air support and interdiction operations, but the photos often had insufficient detail and target resolution. This was partly due to Secretary McNamara’s injunction requiring Yankee Team aircraft to fly at medium altitude (10000 ft = 3048 m) to avoid losses. Proposals to fly reconnaissance well below this limit to obtain more detail of targets and target areas were usually turned down. State, Defense, and White House approval of each Yankee Team mission remained in effect, with exceptions considered case-by-case.

Reconnaissance missions generated another crisis in late November 1964 when NVA ground fire downed an F-100, and then an RF-101C. Gen. Hunter Harris, PACAF Commander, demanded retaliatory strikes with napalm and CBU-2A munitions near Mu Gia Pass. That location was intended for Hanoi to “get the message.” But Admiral Sharp, apparently sensing the unlikelihood administration approval, withheld the request. With the shootdown of the RF-101C, however, he personally recommended to the JCS a retaliatory strike. The joint chiefs also backed retaliation, but Washington, as usual, turned aside the requests for punitive strikes as they had "escalatory overtones." Ambassador Unger halted all Yankee Team and Lucky Dragon U-2 missions over Laos until the JCS completed a review.

With the aerial photography obtained, intelligence personnel were able to identify numerous infiltration routes. NVA manpower and supply infiltration estimates, however, were based on captured Viet Cong interrogation. General LeMay was very positive about the contribution of air power. He was convinced that RLAF operations by US-trained Lao pilots had “paid off,” and Yankee Team raised Laotian morale, and furnished valuable data on Communist infiltration.

USAF RF-101C 'Voodoo'

Operation Barrel Roll

During the 1964 wet season, more evidence of NVA trail activity and hostile actions against reconnaissance missions occurred. General Westmoreland wanted to launch ground surveillance of the Ho Chi Minh Trail, as monsoon weather reduced Yankee Team effectiveness. And, in late November 1964, Ambassador Taylor warned that South Vietnam’s continuing political and military problems required more action. Asserting that the United States was playing a “losing game” in South Vietnam, he outlined several military options. He suggested slowly adding heavier bombings, and greater participation in Laos operations.

Taylor's Phase I proposed one month of heavier airstrikes in the Laotian panhandle, and covert Plan 34A bombings of North Vietnam itself. If the North Vietnamese failed to heed the warning, then Phase II would begin US and Vietnamese Air Force (VNAF) strikes on North Vietnam just above the DMZ, and increase the tempo for six months to get all significant targets. President Johnson approved Phase I for missions along segments of Routes 8, 12, and 121 in the Laotian panhandle, with barracks and strongpoints as secondary targets.

Phase I and II became known as Operation "Barrel Roll." Admiral Sharp alerted Generals Westmoreland, Moore, and Admiral Moorer prior to its start. The first mission was flown in December 1964 by four F-105 Thunderchiefs laden with 750-lb  bombs, CBU-2A bomblets, and AGM-12 Bullpup missiles. Accompanying the strike aircraft were four F-100s for combat air patrol, One  RF-101C  for post strike reconnaissance, two Korat-based F-105s for escort, and two refueling KC-135 tankers. The pilots flew along Route 8 and near the Nape bridge, spotting a vehicle on an apparent nearby sunken bridge serving as a bypass. One F-105 aimed six 750-lb bombs on the bridge, but they missed. The other three fighters struck secondary targets, with results obscured by cloud cover. The mission encountered no NVA ground fire.

Seventh Fleet went into action three days later. F-8 pilots searched for targets in the central Laotian panhandle. Finding none, they hit a bridge two miles east of the junction of Routes 8 and 12. They dropped thirty-two 250-lb bombs, which cut the road west of the bridge, and destroyed eight buildings, although the bridge sustained no major damage. Again, there was no anti-aircraft fire.

A USN F-8 Crusader on a carrier.

New Laos Ambassador Sullivan faulted the first two Barrel Roll missions for insufficient Vientiane coordination. An eight-hour delay in informing Col. Tyrrell failed to alert Air America search and rescue helicopters. (SAR) It did not help avoid interference with RLAF operations. Secondly, bomb damage assessment of PACFLT-destroyed buildings suggested they may have been civilian dwellings. Sullivan insisted on US/RLAF agreement on what constituted authorized targets. Admiral Sharp, concurring, directed that future targets of opportunity show “unmistakable” military activity, or a connection with attacks on clearly identified military convoys and personnel. He tasked General Westmoreland to coordinate authority for future Barrel Roll missions, and follow proven Yankee Team procedures.

If that wasn't bad enough, on a night mission, PACFLT’s A-1H Skyraiders strayed off course from Route 23, and accidentally hit Ban Tang Vai village in Savannakhet Province. They destroyed five houses, damaged seven granaries, and reportedly wounded five civilians and five Lao soldiers. General Thao Ma was highly upset, and Ambassador Sullivan, with sharp words about “undisciplined pilots,” temporarily halted night missions.

In the last three months of 1964, the RLAF flew 724 sorties. And, from May through December, Yankee Team flew 880 missions. Despite this, there was no public or other reaction from Hanoi, and officials concluded the strikes failed to send a signal of American strength. Nonetheless, they believed it had a positive effect as it improved Lao and Thai morale, provided training and terrain familiarity for pilots, caused some defections of Pathet Lao, forced NVA dispersal or abandonment of fixed facilities, and disrupted the PL/NVA counterattacks at Muong Soui and elsewhere.

Operation Steel Tiger

In February 1965, Viet Cong attacked an American barracks and airfield near Pleiku, killing eight soldiers, wounding 104, and destroying several aircraft. This incident led to a decision by President Johnson to make retaliatory airstrikes on North Vietnam, and the "Rolling Thunder" program began. General Westmoreland wanted to consolidate the operations of Yankee Team, Barrel Roll, and Rolling Thunder under a single air program. But, Souvanna Phouma objected because they did not want RLAF involvement with bombing North Vietnam.

The Ho Chi Minh trail problem still persisted, however. The Army solution, ("isolate the battlefield")  was to put a US Army Corps west of the DMZ across the Laotian panhandle, to block the trail. But, the political will for this simply did not exist. Air Force and Navy commanders wanted more air power.

Ambassador Sullivan suggested conducting systematic "chokepoint" strikes at key locations on vital  infiltration routes without diverting aircraft to other NVA supply areas as in the past. But, General Harold K. Johnson, Army Chief of Staff submitted to the president a twenty-one-point program for blunting Communist challenges in Laos and South Vietnam. Included in this program was stepping up Rolling Thunder strikes in North Vietnam, confining Barrel Roll operations to northern Laos, and a new air program to attack communist infiltration via the Ho Chi Minh Trail.

The new program, "Steel Tiger," was authorized by President Johnson in March 1965.  Sullivan requested a rapid air response system to reduce procedural delays for strike clearances. He wanted on-call USAF aircraft at Udorn to hit preselected targets, and those spotted by roving roadwatch teams, some of which would receive radios. Further, he wanted photos processed at Udorn, where they could be collated with other intelligence data. Moore shortly stationed a small number of F-4 and F-105 on-call aircraft at several Thai air bases.

Rules of engagement for Steel Tiger included  enemy targets of opportunity, military vehicular and troop movements and anti-aircraft (AA) guns spotted within 200 m of designated roads. Camp fires and civilian habitations would not be attacked. Fixed installations were to be struck only in connection with attacks on clearly identified military convoys and military personnel, or when pre-briefed as primary and secondary interdiction target. Unexpended ordnance should be dumped in free strike zones. But, the directive eased previous rules permitting more pre-mission visual reconnaissance aircraft equipped with side-looking airborne radar and infrared, and to support more weather, pathfinder, flare, and search and rescue operations.

On April 3, PACAF led off with a two night operations, each mission consisting of a navigation and flare-carrying C-130 BLINDBAT accompanied by two strike B-57s. Scanning several routes under the glare of 126 flares, the pilots reported no significant sighting of enemy traffic. The next day PACAF sent seven B-57s and three escorted RF-101Cs in a daytime attack on Mu Gia Pass. The tactical jet bombers cratered a road and reseeded other routes with bombs. On April 5, four strike and four support F-100 Super Sabres (the latter for MiG combat air patrol) plus two RF-101Cs flew daytime reconnaissance over three routes and hit the Ban Phanop supply depot. The planes dropped seven 750-lb general purpose bombs, and expended four rockets on a building in the depot area. PACAF dispatched its F-105 Thunderchiefs on their first Steel Tiger mission on April 11 against two routes and a military site at Ban Langkhang.  By April 29, the two services had flown 791 Steel Tiger sorties of all types.

A USAF B-57 releasing its payload.

B-57 Bomber

Westmoreland asked for and Sullivan approved stationing of USAF aircraft on strip alert to strike fleeting targets, particularly trucks. In the Barrel Roll and Steel Tiger programs, the ambassador agreed to operations against “targets of opportunity,” provided rules of engagement were met. As a result, four USAF F-4Cs (codenamed BANGO,) were put on fifteen-minute strip alert at Ubon. Shortly after four F-105s (codenamed WHIPLASH,) were similarly placed at Takhli and Korat. On May 9 RLAF T-28s reportedly destroyed two tanks and five trucks, and hoping for a bigger kill, pilots requested  USAF assistance. An hour later, BANGO Phantoms arrived and, with T-28s marking targets, destroyed two more tanks, and damaged two. Pilots reported heavy ground fire with one hit on an T-28 which returned safely to its base. The chief air attache considered the USAF response, coordination, and mission results excellent.

More friendly fire incidents occurred, and Ambassador Sullivan halted all Steel Tiger reconnaissance missions from May 22 until June 7 to work out more stringent operational rules. Strikes on fixed installations, were prohibited unless associated with attacks on troops or similar military targets. All American aircraft overflying Laos had to maintain a minimum altitude of 10000 ft (3050 m,) and avoid the Savannakhet, Pakse, Saravane, Vientiane, and Paksane. Within the Steel Tiger boundary, Yankee Team reconnaissance aircraft were ordered to observe a minimum of 5000 ft (1525 m,) with requests for lower altitudes reviewed by the ambassador and his staff on a case-by-case basis.

Another plan concentrated more tactical air strikes against enemy routes, trails, and redoubts in the southeasternmost section of Laos next to the South Vietnamese border. The plan was translated into a new concept christened "Tiger Hound" by General Westmoreland. The “Tiger” connoted aggressiveness, and “Hound” for "smelling out" the NVA. The concept would extend the “in-country” or South Vietnamese war into this small sector of Laos.

Tiger Hound missions began in December 1965 with USAF-piloted O-1E forward air controllers (call sign HOUND DOG) began flying visual reconnaissance missions, and guiding PACAF F-103, BANGO F-4Cs, and PACFLT and Marine strike aircraft to numerous targets. USAF AC-47 gunships, which besides their attack role, served as flareships and FACs for other aircraft. In addition sectors of Barrel Roll and Steel Tiger were designated as A through G, but in pilot's parlance, Alpha, Bravo, Charlie, Dog, Echo, Foxtrot, and Golf.

The success of Barrel Roll and Steel Tiger were reflected in these 1965 overall statistics: Destroyed 108 trucks, 712 structures, and 201 bridges. These programs damaged 115 trucks, 471 structures, and 174 bridges.

Zones of Interdiction of the Trail.

Truck Busting on the Ho Chi Minh Trail

AC-47 interdiction sorties evolved into a system of truck-busting. Two SPOOKY gunships were scheduled to fly continuous coverage at night.  One aircraft took off at 1800, the other at 2400. The gunships flew a planned schedule allowing at least four contacts per night with each of the roadwatch teams patrolling around the Ho Chi Minh Trail network.

After flying to the designated area, a Lao observer on board the gunship radioed a roadwatch team. If a target was seen in the area, the gunship would drop flares along the road in an effort to find the target. Once a truck was spotted, the gunship went into its strike orbit, and fired away.

The NVA responded with more and better air defense. Communist forces were equipped with various AA weapons including 37-mm guns which outstripped the range of SPOOKY 's miniguns. The NVA had well-organized road security. They used platoons and trained dogs against Laotian watch teams. The road watch and action teams in Military Region IV were composed of 12 men each. Since they could not speak English, signals were used in their communications with the USAF.

AC-47 Gunship "SPOOKY"

AC-47 Gunship "SPOOKY"

Arc Light

The first request for use of B-52 strategic bombers for "saturation bombing" came from General Westmoreland in November 1965. Sullivan concurred, providing Washington authorities gave “iron clad” assurances of no publicity. The first mission was approved and took place in December. Twenty-four B-52s from the 3d Air Division on Guam carried the strike on suspected infiltration targets near the South Vietnamese border. Refueled by SAC KC-135 tankers, the aircraft dropped BLU-3B bomblets and 750-lb bombs. As there were no followup ground patrols of the bombed area, results were indeterminate.

The use of B-52 Stratofortresses would continue under code name "ARC LIGHT." Eventually, the 486th Bomber Squadron would be deployed to the U-Tapao air base in Thailand. These would be used throughout the war, not only for the trail interdiction, but for bombing in North Vietnam as well.

Commando Hunt

The operations Rolling Thunder, Barrel Roll, Steel Tiger, and Tiger Hound continued into 1968. After the North Vietnam bombing halt in late 1968, the Steel Tiger and Tiger Hound programs were consolidated into one called "Commando Hunt." The North Vietnam bombing halt allowed them to shift sorties planned for North Vietnam to southern Laos. This added 480 missions daily against the trail.

This program differed from Steel Tiger in that greater use was made of sensors in the "Igloo White" program. Thousands of  seismic and acoustic sensors had been dropped along the trail to detect traffic, and the signals collected and analyzed at Nakhon Phanom.

Commando Hunt was divided into phases, with each phase covering a wet or dry season. Phases I, III, V, and VII were in the dry seasons up until 1972. The even numbered ones took place in wet seasons from May to October. Phase I struck choke points where multiple roads converged. Mu Gia and Ban Karai passes were included in this. Phase II focused on the trail itself to hit the NVA where it was found. Phase III increased air attacks in southeastern Laos and extended the sensor fields. Monitoring of Tchepone was included. Phase IV returned the emphasis on choke points, and subsequent phases repeated the pattern, with modifications as they were needed.

he most effective was Phase V in the dry season from October 1970 to April 1971. An average of twenty-seven Arc Light strikes and 125 tactical air strikes were conducted daily. In January 1971, 2186 tactical air sorties were flown against suspected truck parks and storage areas resulting in 3720 secondary explosions and fires. The AC-130 Gunship "Spectre" was the most effective at truck busting. An estimated 19000 trucks were destroyed or damaged in Phase V. Indeed during Phase V, the NVA was not able to maintain an activity level in South Vietnam as in previous years.

Conclusion

The US interdiction campaign began very slowly from 1964, but reached a high level in the last few years of the war, particularly in 1971. Despite all of these efforts however, the NVA managed to move enough supplies and troops through the trail to South Vietnam to sustain its initiatives.

References

"Interdiction in Southern Laos 1960- 1968," Jacob Van Staaveren

"The Ho Chi Minh Trail and Operation Commando Hunt: The Failure Of An Aerial Interdiction Campaign," Dong Nguyen Ha

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