Park Chung Hee presided over the Republic of Korea (ROK) longer than any other leader (1961–1979) and he remains the individual most responsible for defining the country's formative features. Having witnessed the worst excesses of Park's later years, many of the early scholars of Korean politics have characterized the whole of Park's long rule as a monolithic dictatorship. One of these pioneering scholars, Sungjoo Han, locates the moment of “the failure of Korean democracy” in 16 May 1961, the very day that Park and his co-conspirators seized control from Prime Minister Chang Myn through a military coup d'état. However, like the man himself, Park's career was complex and highly adaptive. Many historians now distinguish Park's rule into three distinct periods: the first and most tenuous years (1961–63) when he directed the government through a military junta, the Supreme Council for National Reconstruction; the middle years (1963–72) of elected presidential rule, referred to as the “Third Republic”; and the final years (1972–79) of dictatorial rule under the Yusin system, the “Fourth Republic.” In his early years, Park had begrudgingly adhered to a minimally democratic framework before finally turning to formal authoritarianism as the American war in Vietnam came to an end.