This focus on materialism would taint their reputation. The zest with which Thai soldiers sought American goods at the PX stores caught the attention of international journalists. Reports describing the Thai soldiers’ involvement in schemes to sell PX goods to Saigon’s black market appeared in the American press, including in The New York Times. In the early 1970s, during the Senate’s Foreign Relations subcommittee hearings into the Vietnam War, it was revealed that the United States was paying the full cost of Thailand’s deployment. This revelation and the negative PX reports contributed to the Thai troops’ reputation in some histories as “America’s mercenaries.”

This wasn’t entirely off base. Thailand was a significant beneficiary of American largess during the Vietnam War years. Its military-dominated government had been a stalwart ally of the United States from the earliest days of the Cold War, and had committed its territory, people and resources to the American-led campaign against Hanoi and its allies. In return the United States poured $1.1 billion in economic and military aid into Thailand; the United States Agency for International Development gave an additional $530 million.

Thailand hosted seven air bases that launched American military aircraft daily on missions to strike strategic targets in Laos, North Vietnam and South Vietnam. The United States funded the rapid expansion of a naval base and port facilities that brought war-related supplies into the region. At the height of the war, some 50,000 American military personnel were stationed throughout Thailand. Thai entrepreneurs, many with connections to the government, built scores of new hotels, restaurants and bars to serve the waves of free-spending American G.I.s visiting on R&R. The G.I.s added $111 million to the Thai economy. At the war’s end, Thailand kept all of this military equipment and infrastructure. The Buddhist kingdom saw itself rapidly modernized thanks to the war.

The “mercenary” tag has done little to harm the soldiers’ reputation at home. Thailand’s official memorials to its Vietnam War veterans laud battlefield success, military professionalism and honor. The Thai Vietnam War Veterans Memorial in Kanchanaburi evokes the more famous World War II-era monument in Bangkok called Victory Monument. Its bas-relief images show well-armed Thai troops defeating ragtag Viet Cong guerrillas. The Royal Thai Army counts the Vietnam War as one of its proudest moments of the 20th century. The dioramas and displays in the official National Memorial Museum outside Bangkok show Thai troops killing their communist foes in arrangements that stress the successful defense of Thailand.

Less evident today is the terrible cost that Thailand paid for its involvement in the war. In addition to the 351 killed in action and the 1,351 wounded in Vietnam, Thailand sent volunteer troops to Laos in the so-called Secret War, many of whom fought and died under terrible conditions. The Vietnam War and the presence of American military personnel played a role in inciting episodes of political violence in the mid-1970s, notably the horrific massacres of student demonstrators by troops, police officers and vigilante gangs in 1973 and 1976.

Bangkok’s notorious red-light districts catering to Western sex tourists trace their origins to the R&R visits by American troops. Some of these soldiers left behind unacknowledged offspring from short-term relationships with Thai women; many of these children were raised in poverty and ostracization. But these events — and especially their connection to the war — are largely elided from Thailand’s official memorials and histories.