Political map of East Asia and the Western Pacific 1 April 1968 (Vietnam War): At the end of the First Indochina War, Vietnam had been divided between a Communist North (North Vietnam) and a pro-Western South (South Vietnam). From 1959, North Vietnam began infiltrating the South (Vietnam War) with the support of the Viet Cong, South Vietnamese guerrillas, as the part of its effort to unify the country under Communist rule. In response, the US, which had established a presence in the region when the French departed, moved in with its forces in an attempt to prop up the South Vietnamese regime.