Ba joined the NLF (National Liberation Front) and served as a cadre in Tây Ninh province.[1] In the mid-1960s, he was recruited by the South Vietnamese Police Special Branch and from 1969 onwards he was run as a spy by the South Vietnamese and the CIA. He provided his handlers with correspondence and plans from the Central Office for South Vietnam (COSVN), the political and military headquarters that controlled the insurgency in South Vietnam.[1]
At the end of his career, he was serving as the Communist Party secretary for Phu Kuong district, Tây Ninh province with responsibility for recruiting members of the Cao Dai religious sect.[2]
Frank Snepp, who served as a CIA agent at the Embassy of the United States, Saigon from 1969 to the Fall of Saigon in April 1975, described Ba as the most important intelligence asset of the war, saying he was the equivalent of having a spy in Hitler's bunker.[3]
