Vietcong the group of guerillas (=unofficial soldiers) who were supported by the Communist government of North Vietnam during the Vietnam War, and fought against US and South Vietnamese forces. in full Viet Nam Cong San (English; "Vietnamese Communists") Guerrilla force that sought to reunify North and South Vietnam under communist leadership from the late 1950s through 1975. Originally a collection of various groups opposed to the government of South Vietnam's Pres. Ngo Dinh Diem, the Viet Cong became the military arm of the National Liberation Front (1960) and later of the Provisional Revolutionary Government (PRG; 1969). Members were recruited largely from South Vietnam, but they received guidance, weapons, and reinforcements from the north. The Viet Cong's guerrilla war against the South Vietnamese government and its powerful U.S. allies was successful; the U.S. withdrew its troops from Vietnam between 1969 and 1973, and the PRG assumed power in South Vietnam in 1975, following a full-scale invasion. It became part of a National United Front the following year