The United States of America ended World War II in 1945. After 6 years without war, the United States entered Korea, formally a Japanese colony, in 1950. North of the 38th parallel, Soviet Russia backed a Stalinist regime under Kim Il-sung and created the North Korean Peoples' Army. Conversely, The United States backed the president Syngman Rhee, who openly opposed national unity. War broke out on June 25th, 1950 when 75,000 North Korean Peoples' Army soldier crossed the 38th parallel into the south.
The invasion by the north was the first military action of the Cold War. Many people do not realize that because it is thought that the Cold War was strictly between the United States and Soviet Russia. Under General Douglas MacArthur, the United States joined forces with the South Korean army. In the United States it was generally believed that this war was a war against communism itself. Even though the war had started, the United States wanted to seek an armistice treaty with the north in fear of a larger war with Russia or China.
When no treaty was agreed upon, the North Korean army advanced rapidly. The most vital location in the war effort was the port of Pusan. If the North Koreans took this port, they would have a severe advantage over the war. General Walton Walker and the 8th United States army rallied and held the bridge.
The number of deaths in this war is uncertain, but it is believed that around 5 million soldiers and civilians lost their lives. The Korean peninsula was divided at the 38th parallel to form two independent countries. To this day, there is a heated, yet dormant, conflict between North Korea and South Korea. The United States is still on the side of the south, while North Korea has no allies. However, North Korea's strongest diplomatic relationship is with China.