He participated in guerrilla-warfare missions in Laos in 1966 and 1967 and was appointed chief of the Special Thai Ranger Army, a volunteer unit which carried out clandestine, anti-communist guerrilla operations financed by the US Central Intelligence Agency against the North Vietnamese Army along the Ho Chi Minh Trail in the Kingdom of Laos, in 1968. Two years later, he was appointed leader of a secret seven-man unit which carried out extrajudicial killings. "The assignment was to kill the leaders of communist groups all over Thailand", he told a reporter, and claimed to have assassinated many suspected communists.