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.
North Korea–South Korea relations
The US government took the issue to the United Nations, which led to the formation of the United Nations Temporary Commission on Korea (UNTCOK) in 1947. The Soviet Union opposed this move and refused to allow UNTCOK to operate in the North. UNTCOK organised a general election in the South, which was held on May 10, 1948. The Republic of Korea was established with Syngman Rhee as President, and formally replaced the US military occupation on August 15. In North Korea, the Democratic People's Republic of Korea was declared on September 9, with Kim Il-sung, as prime minister. Soviet occupation forces left the North on December 10, 1948. US forces left the South the following year, though the US Korean Military Advisory Group remained to train the Republic of Korea Army.