South Vietnam, officially the Republic of Vietnam, was a country that existed from 1955 to 1975, the period when the southern portion of Vietnam was a member of the Western Bloc during part of the Cold War. It first received international recognition in 1949 as the State of Vietnam within the French Union, with its capital at Saigon, before becoming a republic in 1955. South Vietnam was bordered by North Vietnam to the north, Laos to the northwest, Cambodia to the southwest, Thailand across the Gulf of Thailand to the southwest. Its sovereignty was recognized by the United States and 87 other nations, though it failed to gain admission into the United Nations as a result of a Soviet veto in 1957.
The end of the Second World War saw anti-Japanese Việt Minh guerrilla forces, led by communist fighter Ho Chi Minh, proclaiming the establishment of the Democratic Republic of Vietnam in Hanoi in September 1945. In 1949, anti-communist politicians formed a rival government in Saigon led by former emperor Bảo Đại. A 1955 referendum on the state's future form of government was highly contested and resulted in the deposal of