Kim Il Sung- Kim Il Sung was the president of communist North Korea and the longest-serving head of state in the twentieth century. Sung wanted to unify North and South Korea by force, Joseph Stalin (Soviet Union leader) and Mao Zedong (China's leader) supported him conditionally for an invasion of South Korea. After basically conquering the South, his authoritarian government was almost destroyed by an American counterattack in fall 1950, and he was only saved because China intervened.