Foreign relations of South Korea
On January 18, 1952 The first president of South Korea Syngman Rhee declared that the vicinity of Dokdo was a territory of South Korea (Syngman Rhee line). Subsequently, some 3,000 Japanese fishermen who conducted fishery operations in this vicinity were captured. This incident, called the Dai Ichi Daihoumaru Ship case strained relations between South Korea and Japan.
Division of Korea
With the onset of the Cold War, negotiations between the United States and the Soviet Union failed to lead to an independent and unified Korea. In 1948, UN-supervised elections were held in the US-occupied south only. Syngman Rhee won the election while Kim Il-sung was appointed as the leader of North Korea. This led to the establishment of the Republic of Korea in South Korea, which was promptly followed by the establishment of the Democratic People's Republic of Korea in North Korea. The United States supported the South, the Soviet Union supported the North, and each government claimed sovereignty over the whole Korean peninsula.