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 the Joseon dynasty
The Chinese defeat in the 1894 war led to the Treaty of Shimonoseki between China and Japan, which officially guaranteed Korea's independence from its tributary status with China. For Japan, it was a step toward regional hegemony in Korea. After that, Korea built the Independence Gate and stopped paying tributes to the Qing dynasty. The Joseon court, pressured by encroachment from larger powers, felt the need to reinforce national integrity and declared the Korean Empire in 1897. Gojong assumed the title of emperor in order to assert Korea's independence. He tried to promote the Gwangmu Reform, but failed because of opposition from the general populace and the Japanese.