Shortly after the outbreak of the Korean War, the United States determined that Soviet Union was the real main body of the attack. US intervened the war to save her prestige and South Korea. US intervention to the Korean war defended Japan and Taiwan as well. Soviet boycotted the UN Security Council which had enabled the establishment of United Nations Command and had despatched UN forces to Korea. Stalin tried to conceal Soviet’s relevance to Korean War. US deployed 24th Division to the north of Daejon in the twentieth days after the outbreak of the war to defend the attack of North Korean army. It reflected the US determination and will to fight against Soviet invasion. In the middle of July 1950, military control of South Korean army was transferred to the General McArthur who was commander of UNC and US Far Eastern Command. Also in December 1950, military control of North Korean army was transferred to the Korea-China Allied Forces Command which was under the command of General P’eng Tehuai. Korean War became international war between US and China. After the Chromite Operation and recovery of Seoul by UNC, the advance to the north of the 38th parallel began. The march to the north brought international dispute whether it had validity of international law to occupy North Korea. Disputes over who controls the Occupied North Korean area created conflict between US and South Korea. UNC handled the administration over the occupied North Korea area. China’s intervention to the Korean War was based on the North Korea-China relations. It was formed through the history of anti-Japanese struggle and cooperation during Chinese civil war. There was Russia-China-North Korea’s mutual understanding before the war that China should intervene in North Korea when the military situation worsened. During the war, Soviet deployed several air forces to defend Korea-China border line. Soviet also offered military and economic aid to China and North Korea. When the Chinese Communist Forces recaptured Seoul in January 1951, there was the conflict among communist regimes. North Korea and Soviet insisted to advance down to Pusan to unite Korea peninsular, but China refused the advancement because her motivation to join the war was to recover the pre-war situation and secure the buffer zone between China and Korea. After the retreat from North Korea and defeat by CCF, US was desperate enough to consider the use of atomic-bomb and establish a government-in-exile out of Korean peninsular. After the recapture of Seoul by UNC in Spring of 1951, it was evident that overwhelming victory of one side and landslide defeat of the other side were impossible. It meant the de-facto end of the war, but the war was continued to save each other’s political face.