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.
North Korea
Soviet general Terentii Shtykov recommended the establishment of the Soviet Civil Authority in October 1945, and supported Kim Il-sung as chairman of the Provisional People's Committee for North Korea, established in February 1946. During the provisional government, Shtykov's chief accomplishment was a sweeping land reform program that broke North Korea's stratified class system. Landlords and Japanese collaborators fled to the South, where there was no land reform and sporadic unrest. Shtykov nationalized key industries and led the Soviet delegation to talks on the future of Korea in Moscow and Seoul. In September 1946, South Korean citizens rose up against the Allied Military Government. In April 1948, an uprising of the Jeju islanders was violently crushed. The South declared its statehood in May 1948 and two months later the ardent anti-communist Syngman Rhee became its ruler. The Democratic People's Republic of Korea was established in the North on 9 September 1948. Shtykov served as the first Soviet ambassador, while Kim Il-sung became premier.