<P> Nguyen Cao Ky was a senior army officer and a former politician of Republic of Vietnam . He served as a prime minister (1965 - 1967) and Vice President (1967 - 1971) of the Republic of Vietnam . From an ally, he then became the opponent of President Nguyen Van Thieu and was mostly sidelined during Thieu's presidency . Ky had been seen as an aggressive anti-Communist person in the period before 1975 and but then was regarded as a symbol of national reconciliation by the Vietnamese Communist Party since 2004 when he became the first South Vietnamese leader returning to the country . </P> <P> Thieu was the Leadership Committee Chairman (1965 - 1967) and President of the Republic of Vietnam (1967 - 1975). In 1963, Thieu joined a military coup to overthrow Diem . During his years as president, Thieu was accused of indulging in corruption . His struggle for power with Ky led to the decisions of side - lining Ky's supporters and choosing loyalists instead of decent commanders to lead the Army of Public of Vietnam (APVN) forces . He strongly opposed the Paris Peace Accords (1973) and publicly blamed the U.S not keeping its promise for fall of Saigon and South Vietnam in 1975 . </P> <Ul> <Li> Ngô Đình Diệm was the President of South Vietnam from 1955 until his assassination in 1963 . </Li> <Li> Ngô Đình Nhu was Diệm's younger brother and generally regarded as the architect of the Ngô family's rule . </Li> <Li> Dương Văn Minh led the South Vietnamese Army under President Diệm and was briefly leader of South Vietnam in 1963 and 1975 . He was the last president . </Li> <Li> Nguyễn Thành was a general who was in power from early 1964 to 1965 . </Li> <Li> Nguyễn Văn Thiệu was the President of South Vietnam from 1967 to 1975 . </Li> <Li> Nguyễn Cao Kỳ was the Prime Minister of South Vietnam from 1965 to 1967 and the Vice President from 1967 to 1971 . </Li> <Li> Trần Văn Hương was the second to last President of South Vietnam before its surrender in 1975 . </Li> </Ul> <Li> Ngô Đình Diệm was the President of South Vietnam from 1955 until his assassination in 1963 . </Li>

Who was president of south vietnam during the war
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