The Supreme Council overthrew the Second Republic of Korea in the May 16 coup in May 1961 and established a provisional military government composed largely of officers who were involved in or supportive of the coup. The Supreme Council was headed by the Chairman, the "de facto" head of government with dictatorial powers, while President Yun Posun was retained as a figurehead. The Supreme Council prioritized South Korea's economic development and political stability, suspending the National Assembly and most political freedoms, and founding the Korean Central Intelligence Agency to combat pro-North Korean and other anti-government activity. Park Chung-hee served as Chairman of the Supreme Council from July 1961 until his victory in the 1963 South Korean presidential election, and the Supreme Council was dissolved upon the inauguration of the Third Republic of Korea in December 1963.