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.
South Korea–Taiwan relations
The Sixth Republic of South Korea furthered the Miracle on the Han River to the Economy of South Korea and opened diplomacy to Communist Nations (including building the foundation of Inter-Korean relations and accepting co-existence with North Korea by entering the United Nations ). Seoul also hosted the 1988 Summer Olympics. President Roh Tae-woo's next political ambition was to begin implementing Realpolitik with the neighboring countries in Northeast Asia.
South Korea's movement away from anti-communist foreign policy to improve relations with nearby communist countries resulted in a deterioration of relations with ROC. This change was introduced to appease North Korea and ease the political anxiety and softens military tension in the Korean Peninsula; Korea hoped to enable the possibility of a peaceful reunification in the Korean peninsula. As normalization began, ROK transferred diplomatic recognition from ROC to the PRC, and confiscated the property of the ROC embassy, transferring it to the PRC. Taiwan is a member of Property Rights Alliance. On 17 September 1991, the PRC withdrew its objection to South Korean membership in the United Nations. Republic of Korea was the last Asian country with formal diplomatic relations with ROC.