This paper examines the rise and fall of 5th Republic headed by Doo Hwan Chun and the birth of 6th Republic led by Tae Woo Roh focusing on the role played by the U. S. during this period. There has been wide spread suspicion in South Korea over the U. S. position taken during 12․12 mutiny in 1979 and Kwangju massacre in May 1980. Through declassified U. S. governmental documents, American News Papers and the memoirs of former U. S. ambassador and U. S. military commander in South Korea, this paper compares the selectivity of the U. S.’s mode of intervention. It is almost impossible to draw the line between ‘positive support’ and ‘interference’ in South Korean politics by America. It is one thing the U. S. had intelligence over South Korean military maneuvering in 12․12 incident and Kwangju massacre, and it is quite another whether Americans had any leverages and time to intervene in those processes. In order to contain the wide spread Anti-American sentiments that could develop into Anti-Americanism in South Korea, Americans both in Washington and Seoul directly and openly intervened in the ‘civilianizing’ Korean politics. Kwangju uprising taught us that only vehement and endless struggle could guarantee internal and external freedom. In order to consolidate South Korean democracy, it is necessary to normalize relations with U. S. as well as with North Korea.