1963 South Vietnamese coup d'état

In November 1963, President Ngô Đình Diệm and the Personalist Labor Revolutionary Party of the Republic of Vietnam (South Vietnam) were deposed by a group of CIA-backed Army of the Republic of Vietnam officers who disagreed with Diệm's handling of the Buddhist crisis and the North Vietnamese and Viet Cong threat to South Vietnam. In South Vietnam, the coup was referred to as Cách mạng 1-11-63 ("1 November 1963 Revolution").

The Kennedy administration had been aware of the coup planning, but Cable 243 from the United States Department of State to U.S. Ambassador to South Vietnam Henry Cabot Lodge Jr. stated that it was U.S. policy not to try to stop it. Lucien Conein, the Central Intelligence Agency's liaison between the U.S. Embassy and the coup planners, told them that the U.S. would not intervene to stop it. Conein also provided funds to the coup leaders.

The coup was led by General Dương Văn Minh and started on 1 November 1963. It proceeded smoothly, for many loyalist leaders were captured after being caught off-guard, and casualties were light. Diệm was captured and assassinated the next day, along with his brother and advisor Ngô Đình Nhu.