The Communist insurgency in Thailand was a guerrilla war lasting from 1965 to 1983 as the Communist Party of Thailand rebelled against Thailand's anti-communist governments.
Communism had been banned in Thailand from 1933 to 1946, when Pridi Banomyong repealed the anti-communist act and established relations with the Soviet Union after World War II. Banomyong was ousted in the 1947 Thai coup d'etat, and the suppression of a 1949 palace rebellion in Banomyong's favor convinced the Communist leadership to make better preparations for a future rebellion. In 1952, the government passed a new anti-communist act after a failed leftist rebellion. The CPT stockpiled weaponry in rural areas amid the Korean War and formed the Peace Committee of Thailand as a pacifist front, spreading anti-American sentiment throughout the country. In 1960, North Vietnam created a training camp for Thai and Laotian volunteers in Hoa Binh, training 400 cadres in the first year alone. The CPT issued a manifesto demanding the removal of American personnel from the country on 8 December 1964, also calling for regime change. From 1961 to 1965, Thai communist insurgents carried out 17 political assassinations, but it was not until the summer of 1965 when Thai militants began engaging security focres.
In November 1965, CPT insurgents graduated from minor violent incidents and began ambushing Thai patrols. The insurgency spread from Nakhon Phanom Province to other parts of Thailand in 1966, although 90% of the insurgency was confined to the country's northeast. On 14 January 1966, the CPT called for a people's war in Thailand, resulting in an escalation of violence. Although the CPT launched five attacks on US Air Force bases in Thailand, American involvement in the conflict remained limited due to the USA's preoccupation with the Vietnam War. Remnants of the Chinese Nationalist 49th Division joined the anti-communist struggle in Thailand after retreating through Burma and Yunnan, and they traded in opium with the tacit approval of the government. Nationalist troops aided Thai government forces in counter-insurgency operations, but their opium dealing resulted in the 1967 Opium War. The government responded to warlord Khun Sa's rebellion against the KMT by destroying a number of villages and resettling suspected communists, providing new recruits to the CPT.
From 1972 to 1974, the Thai military carried out Operation Thong Pha Phum in Chiang Rai Province, followed by Operation Sam-Chai in Phetchabun, Phitsanulok, and Loei. 12,000 troops were deployed to the country's northern provinces in 1972, killing over 200 militants. In late 1972, the government's Red Drum killings saw between 200 and 3,000 communist sympathizers be executed in Phatthalung Province in southern Thailand. In 1976, government forces cracked down on a leftist student demonstration at Thammasat University in Bangkok, resulting in the killing of 46 students and wounding of 167 in the Thammasat University massacre. As Chinese-Vietnamese relations declined after 1979, the pro-Vietnamese wing of the CPT seceded from the main party to form the Pak Mai faction, and, in 1980, Prime Minister Prem Tinsulanonda offered the communist guerrillas an amnesty. By 1983, the insurgency had come to an end.