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 received international recognition in 1949 as the "State of Vietnam", which was a constitutional monarchy. The country was renamed the "Republic of Vietnam" in 1955. Its capital was Saigon. 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, and the Philippines, Malaysia, Brunei, and Indonesia across the South China Sea to the east and southeast.
The Republic of Vietnam was proclaimed on 26 October 1955, with Ngô Đình Diệm as its first president, after having briefly served as premier under Emperor Bảo Đại who was exiled. Its sovereignty was recognized by the United States and 87 other nations. It had membership in several special committees of the United Nations, but its application for full membership was rejected in 1957 because of a Soviet veto.