The Korean War arose from the division of Korea at the end of World War II and from the global tensions of the Cold War. A United Nations force led by the U.S. fought on behalf of South Korea against North Korea and its Chinese and Soviet Union allies.
Twenty-one countries of the United Nations contributed to the defense of South Korea. The U.S. constituted 88 percent of the military force fighting on behalf of South Korea. The fighting ended in July 1953 when an armistice agreement was signed. The agreement established a 2.5-mile-wide fortified buffer zone between the north and south. The war is viewed as both a civil war and a proxy conflict in the Cold War between the U.S. and the Soviet Union. While it did not commit forces to the conflict directly, the Soviet Union did provide strategic planning, weapons and materials for both the North Korean and Chinese armies.