The Bangkok Plot, also known as the "Dap Chhuon Plot", was an international conspiracy in Cambodia in the late 1950s. The goal of the conspiracy was to topple Prince Norodom Sihanouk of Cambodia. It was allegedly initiated by right-wing politicians Sam Sary, Son Ngoc Thanh, the regional Cambodian warlord and governor Dap Chhuon, and the governments of Thailand and South Vietnam with possible involvement of US intelligence services. The Bangkok Plot, and its politics, is still influencing Cambodian politics today.
According to the account later to be given by Sihanouk, the coup was to be carried out by Thanh's Khmer Serai irregulars, largely from the Khmer Krom minority of southern Vietnam. The Khmer Serai were massed in the southern border areas while Chhuon - who for the past few years had been a trusted associate of Sihanouk - was to start an uprising in the north-east. In early February 1959, Admiral Harry Felt, General Lawton Collins and Colonel Edward Lansdale all visited Chhuon's base in Siem Reap.
Sihanouk's intelligence services discovered details of the plot and on February 21, 1959 dispatched a battalion of troops to arrest Chhuon. Chhuon fled, but a US citizen and alleged CIA radio operator, Victor Matsui, was captured. Chhuon was later apprehended, interrogated, and died "of injuries" in somewhat murky circumstances before he could be properly interviewed. Sihanouk later alleged that his Minister of Defence, Lon Nol, had Chhuon shot to prevent being implicated in the coup.
Sihanouk arranged that pictures of Chhuon's corpse be posted on a main Phnom Penh thoroughfare. Of the other main plotters, Sary disappeared in 1962, while Thanh went on to have involvement in Lon Nol's post-1970 government before leaving for Vietnam. Chhuon's brother Slat Peou, a member of Sihanouk's delegation at the United Nations and a friend of Matsui, was executed for treason.
Sihanouk, an amateur film director, later used the plot as the basis for his film Ombre sur Angkor (Shadow over Angkor) from 1968. He regarded it as conclusive evidence that the US intended to destabilise his regime, which had established relations with communist China.
- Prados, J. Lost crusader: the secret wars of CIA director William Colby, Oxford University Press, 2003, p.67
- David Hutt (16 August 2018). "Hun Sen's power grab guided by Cambodian history". Asia Times. Retrieved 20 January 2019.
- Norodom Sihanouk, My War with the CIA, Pelican, p.108
- Prados, p.68
- "Ombre sur Angkor". IMDb. Retrieved 20 January 2019.
- Sihanouk, p.111