The American headquarters in Saigon requested, and received, authorization to control bombing in the area adjacent to South Vietnam's northern provinces in Operation Tiger Hound on 3 December 1965.

The American public (who had been reassured by President Lyndon B. Johnson and the Pentagon that the communists were incapable of launching any such actions) were stunned by the size and ferocity of the offensive.

The interdiction campaign against the enemy logistics corridor was massively expanded due to the increased number of U.S. aircraft (approximately 500 planes) made available by the closure of Rolling Thunder.

"[citation needed] The physical barrier was to be backed up by air-dropped and hand-emplaced acoustic and seismic sensors that would provide both warning and location of enemy movements.

The hand emplacement of sensors and bomb damage assessment missions were to be carried out by the reconnaissance teams of the highly classified Military Assistance Command, Vietnam Studies and Observations Group (SOG), which already operated "over the fence" in Laos.

[15] The anti-infiltration effort would be supported by MSQ-77 Combat Skyspot, a ground-based radar bombing system first introduced in Southeast Asia in 1966 to direct B-52 strikes in poor weather or in complete darkness.

[18] The PAVN siege of the U.S. Marines at the Khe Sanh Combat Base, in western Quang Tri Province, South Vietnam, provided the opportunity for an operational test.

[citation needed] The immediate result of 11 November bombing halt was that the average daily sortie rate over southern Laos rose to 620 per day before the new campaign had even begun.

The Ho Chi Minh Trail (controlled by the 259th PAVN Logistical Group) consisted of a labyrinth of dirt roads, bicycle and foot paths, bypasses, storage areas, workshops, and truck parks that stretched from the mountain passes of North Vietnam, through the panhandle of Laos, and into east central Cambodia.

[25] By the end of Commando Hunt I, the first dry season offensive of the campaign (15 November 1968 to 20 April 1969), the Air Force estimated that 7,322 enemy trucks had been destroyed.

The ambassador (with the full backing of the State Department and the CIA) maintained a firm hold over all military operations conducted within the supposedly "neutral" Kingdom of Laos.

[citation needed] On the other side of the fence, the North Vietnamese transported and/or stored 70,000 tons of supplies in 3,000 trucks with a net loss of 13.5 percent during the year.

"[39] The motivating factor became evident in April, when U.S. and South Vietnamese ground forces launched an incursion into the PAVN base areas lining the eastern border of Cambodia.

[40] Missions conducted by CIA-backed Laotian irregulars and Thai volunteers operating on the western flank of the trail (and the Lon Nol coup in Cambodia) prompted PAVN to launch offensives in Laos to protect and expand their system.

The watertight drums were launched en masse from tributary streams into the main channel, floated downstream, and were recovered by systems of nets and booms.

By 1970 the North Vietnamese were making intense use of streams and rivers to supplement their logistical route, especially in the rainy season, when the water levels rose and the roadways became impassable mires.

During Commando Hunt III the Seventh and Thirteenth Air Force estimated that 700 23-mm and 37 mm weapons, most of them radar-guided, were defending the trail system in southern Laos.

[46] This evolution in aircraft was a "dynamic reaction between opposing forces which led to a refinement of the tactics of employing round the clock interdiction and prompted development of specialized night attack systems.

"[48] During Commando Hunt V (10 October 1970 to 30 April 1971) Air Force intelligence claimed 16,266 trucks destroyed and another 7,700 damaged during the dry season offensive.

The lower figures were attributed to the fact that many PAVN air defense units had been moved to the Tchepone area to support the counteroffensive against the South Vietnamese Operation Lam Son 719.

By the time of the opening of Commando Hunt VI, that figure had decreased to 1,199 aircraft and this number dropped to 953 before that phase was completed; Second, this state of affairs was exacerbated by the withdrawal of sorties to conduct missions for Operation Freedom Deal in Cambodia.

[55] Commando Hunt VI, launched during the wet season, was hampered by heavy rain and the arrival of two typhoons which threw off both the PAVN logistical effort and U.S. attempts to interdict it.

[citation needed] Air Force planners believed that Operation Commando Hunt VII (1 November 1971 to 29 March 1972) would be the most fruitful of the entire campaign.

[citation needed] American analysts were elated when they discovered that the number of trucks ordered by North Vietnam from its communist allies in late 1971 exceeded those of previous years.

This conventional attack, backed by armor, heavy artillery, and anti-aircraft units (including SAMs) rolled over the two northernmost provinces of South Vietnam while two smaller offensives were launched in central and southern parts of the country.

With the signing of the Paris Peace Accord in March 1973, the Vietnam War finally came to an end for the U.S.[citation needed] The goal of the Commando Hunt campaigns was not to halt infiltration, but to make the North Vietnamese pay too heavy a price for their effort.

First, there were the political constraints imposed by Washington that limited the entire American effort in Southeast Asia (the continued fiction of Laotian and Cambodian "neutrality", failure to disrupt the trail with U.S. ground forces when it would have made a difference, etc.)

"[63] At the end of the Commando Hunt campaigns the Air Force intelligence service claimed that 51,000 trucks and 3,400 anti-aircraft guns were destroyed in all seven operations.

[64] Statistics, however, proved no substitute for strategy and, "for all the perceived success in that numbers game, the Air Force succeeded only in fooling itself into believing that Commando Hunt was working.

[65] Regardless of the constant American belief that its enemy was on the verge of collapse, PAVN maintained and expanded its logistical flow to combat units in the field and managed to launch major offensives in 1968 and 1972 and a counteroffensive in 1971.