As the so-called Cold War between the communist Soviet Union and the United States deepened, Korea became one of the first casualties. Northern Korea moved toward the left, while the southern half moved toward the right. This development posed a problem because the United States and the Soviet Union, when they had been allies against Japan, had agreed that Korea's division would be only temporary. However, it increasingly appeared to Koreans that reunification was becoming more difficult because of the clash of Soviet and U. S. ideologies.
From the perspective of the United States, it appeared that if Korea were reunited, communist-inspired People's Committees would reappear, and that Korea would be united under communism with the help of the Soviet Union. That possibility was unacceptable to the United States. The U. S. government decided it would be better to keep the southern half of Korea noncommunist than to risk having the entire country fall under communism. For this reason, the plans for trusteeship, which depended upon cooperation between the United States and the Soviet Union, were abandoned.
The United States thus began plans to create a separate South Korean nation that would make Korea's division at the 38th parallel permanent. This was an outcome that Koreans had never envisaged. They had been freed from Japanese domination only to find their country split in two. Korean nationalism, which had been directed against the Japanese, now shifted to focus on reunification.
By 1948 the hopes for a reunified Korea were already dim. Syngman Rhee had been elected president of a separate South