South Korea–United States relations
Following Japanese surrender at the end of the Second World War, the Allied Powers divided the Korean peninsula along the 38th Parallel with two occupation zones with the United States in the south, and the Soviet Union in the north that would later become North Korea. On August 15, 1948, the southern half of Korea declared independence as the Republic of Korea with Syngman Rhee as president. The United States recognized the Republic of Korea as an independent state on January 1, 1949 and diplomatic relations between two countries were established on March 25 in the following year.
Cross-border skirmishes and raids at the 38th Parallel escalated into open warfare when the North Korean forces invaded South Korea on June 25, 1950. The Korean War broke out when North Korea invaded South Korea. In response, 16 member countries of the United Nations, including the United States, came to the defense of South Korea. It was the first significant armed conflict of the Cold War with extensive deployment of American and other troops.
History of South Korea
Korea was administratively partitioned in 1945, at the end of World War II. As Korea was under Japanese rule during World War II, Korea was officially a belligerent against the Allies by virtue of being Japanese territory. The unconditional surrender of Japan led to the division of Korea into two occupation zones (similar to the four zones in Germany), with the United States administering the southern half of the peninsula and the Soviet Union administering the area north of the 38th parallel. This division was meant to be temporary (as was in Germany) and was first intended to return a unified Korea back to its people after the United States, United Kingdom, Soviet Union, and Republic of China could arrange a single government for the peninsula.