the initial plan of a unified Korea in the 1943 Cairo Declaration, escalating Cold War antagonism between the Soviet Union and the United States eventually led to the establishment of separate governments, each with its own ideology, leading to the division of Korea into two political entities in 1948: North Korea and South Korea. In the South, Syngman Rhee, an opponent of communism, who had been backed and appointed by the United States as head of the provisional government, won the first presidential elections of the newly declared Republic of Korea in May. In the North, however, a former anti-Japanese guerrilla and communist activist, Kim Il-sung, was appointed premier of the Democratic People's Republic of Korea in September. In October, the Soviet Union declared Kim Il-sung's government as sovereign over both parts. The UN declared Rhee's government as "a lawful government having effective control and jurisdiction over that part of Korea where the UN Temporary Commission on Korea was able to observe and consult" and the Government "based on elections which was observed by the Temporary Commission" in addition to a statement that "this is the only such government in Korea." Both leaders began an authoritarian repression of their political opponents inside their region, seeking for a unification of Korea under their control. While South Korea's request for military support was denied by the United States, North Korea's military was heavily reinforced by the Soviet Union. Korean War On 25 June 1950, North Korea invaded South Korea, sparking the Korean War, the Cold War's first major conflict, which continued until 1953. At the time, the Soviet Union had boycotted the United Nations (UN), thus forfeiting their veto rights. This allowed the UN to intervene in a civil war when it became apparent that the superior North Korean forces would unify the entire country. The Soviet Union and China backed North Korea, with the later participation of millions of Chinese troops. After an ebb and flow that saw both sides facing defeat with massive losses among Korean civilians in both the north and the south, the war eventually reached a stalemate. During the war, Rhee's party promoted the One-People Principle, an effort to build an obedient citizenry through ethnic homogeneity and authoritarian appeals to nationalism. The 1953 armistice, never signed by South Korea, split the peninsula along the demilitarized zone near the original demarcation line. No peace treaty was ever signed,