Since 1910, Korea had been under control of the Japanese government. In 1945, the communist Soviet Union invaded North Korea, quickly forcing the Japanese to surrender. The United States, sticking true to their foreign affairs policies regarding communism; "In helping free and independent nations to maintain their freedom, the United States will be giving effect to the principles of the Charter of the United Nations" (Truman Doctrine, 1947), immediately moved troops into South Korea, fearing the Soviets would make a move for the southern portion of the Korean peninsula as well. Attempting to avoid a long-term decision about the fate of Korea, the U.S. and the Soviet Union agreed to split the Korean peninsula into two halves, divided by the 38th parallel. The United States was determined to not give an inch of space to communism, both at home and abroad. North Korea remained under control of the Soviet Union, while South Korea was given to the United States. .
Tensions quickly grew between the North and South, as powerful leaders arose in both territories; Kim Il Sung imposing a communist regime in the North and national exile Syngman Rhee establishing the Republic of Korea in the South. Although the U.S. had begun to withdraw troops from Korea as early as 1948, they were forced to remain, as communist North Korea threatened to invade South Korea. Backing his unwavering support of Syngman Rhee's government, and other free nations around the world, Truman said, "If we falter in our leadership, we may endanger the peace of the world -- and we shall surely endanger the welfare of our own nation" (Truman Doctrine, 1947). On June 25, 1950 fighting broke out along the 38th parallel, as North Korean troops pushed their way into South Korea and took the city of Seoul. Immediately, the newly formed United Nations Security Council kicked into action, labeling the invasion a "breach of the peace".
