The Korean War was one of several military conflicts that occurred during the Cold War, as the United States and its allies attempted to stop the spread of communism. The conflict began on 25 June 1950, when North Korea, a communist nation, invaded South Korea.
Before the conclusion of World War II, North and South Korea were a single country known as Korea. After the war, Korea became a two country. By invading South Korea, North Korea hoped to reunite the two countries as one country under communism.
With North Korea's invasion of South Korea, the United States feared the spread of communism. Determined to stop North Korea, the United States sought permission from the United Nations to support the South Korean government's military.