The Kingdom of Thailand, under the administration of military dictator Field Marshal Thanom Kittikachorn, took an active role in the Vietnam War.

[3]: 26 In October 1967 the Royal Thai Volunteer Regiment (Queen's Cobras) was sent to Camp Bearcat at Bien Hoa, to fight alongside the Americans, Australians, New Zealanders and South Vietnamese.

[3]: 49 In December 1969 the effects of the withdrawal of the Philippine Civic Action Group, Vietnam, and antiwar sentiment in the US were felt in Thailand as elsewhere.

He also stated that the subject had been discussed with South Vietnamese Foreign Minister Tran Chan Thanh, and had been under consideration for some time.

The withdrawal plans were confirmed and even elaborated upon through a Royal Thai government announcement to the United States and South Vietnam on 26 March 1971.

The three LST's Landing Ship, Tank (LSTs) of the Sea Horse unit would be withdrawn in April 1972 and Victory Flight would be pulled out by increments during the period April-December 1971.

[3]: 49–51 The official American military presence in Thailand started in April 1961 when an advance party of the USAF 6010th Tactical (TAC) Group arrived at Don Muang Royal Thai Air Force Base at the request of the Thai government to establish an aircraft warning system at Don Muang.

[6] The USAF would eventually use 8 airbases in Thailand: Don Muang, Korat, Nakhon Phanom, Nam Phong, Takhli, Ubon, Udorn and U-Tapao.

The People's Army of Vietnam Special Forces infiltrated into Thailand several times to attack these airbases, with a 1972 raid on U-Tapao seeing three Boeing B-52 Stratofortress bombers being damaged with several sappers and a Thai sentry killed.

Thai entrepreneurs built scores of new hotels, restaurants and bars to serve the waves of free-spending American G.I.s, causing foreign funding to flow into the country.

At the war's end, Thailand kept all military equipment and infrastructure left by the Americans, aiding in the country's modernization.

[2] On 14 October 1973 following the 1973 Thai popular uprising, former Supreme Court Judge Sanya Dharmasakti, then chancellor and dean of the faculty of law at Thammasat University, was appointed prime minister by royal decree, replacing the succession of staunchly pro-American and anti-Communist military dictatorships that had ruled Thailand previously.

With the fall of both Cambodia and South Vietnam in April 1975, the political climate between Washington and the government of PM Sanya had soured.