Answer
Ngô Đình Diệm was the President of South Vietnam when Nguyễn Văn Thơ was Vice President. Ngô Đình Diệm was a Roman Catholic who ruled South Vietnam from 1954 to 1963. He was a staunch anti-communist and his rule was marked by political repression and economic stagnation. Diệm was overthrown and assassinated in a coup d'état in 1963.