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.
Korean nationalist historiography
The surrender of Japan at the end of World War II handed Korea its independence, but the peninsula was immediately divided into ideologically opposed regimes in North and South Korea. At first, Marxist historians focusing on class analysis dominated historical writing in the north, whereas Syngman Rhee's staunchly anti-Communist government (1948–1960) also made the notion of "minjok" less central to historiography in the south. In North Korea class analysis was displaced by nationalist analysis in the 1950s, soon after the Korean War. In South Korea, the fall of the Rhee regime in 1960 and the anti-Japan protests triggered by the normalization of diplomatic ties with Japan in 1965 also reinstated the "minjok" as a "unifying framework" for developing an anti-colonial historiography. Since then, historical studies in both North and South have displayed a "pervasive and intense nationalistic tone" despite ideological differences between the two countries. This shared historical outlook has served as a backdrop to North Korea–South Korea relations, as in June 2000 when both Korean heads of state stated that Korean unification was a historical imperative.