1945: The Division of the Korean People
Following Japan’s defeat in 1945 the Soviet Union and United States agreed to split the post-war control of the Korean peninsula between themselves. On August 10, 1945 two young U.S. military officers drew up a line demarcating the U.S. and Soviet occupation zones at the 38th parallel. The divide should have been temporary, a mere footnote in Korea’s long history, but the emergence of the Cold War made this a seminal event. Seeking to ensure the maintenance of their respective influences in Korea, the U.S. and USSR installed leaders sympathetic to their own cause, while mistrust on both sides prevented cooperation on elections that were supposed to choose a leader for the entire peninsula. The United States handed control over the southern half of the peninsula to Syngman Rhee, while the Soviet Union gave Kim Il-sung power over the north. In 1948, both sides claimed to be the legitimate government and representative of the entire Korean people.
August 15, 1948
Syngman Rhee declares the formation of the Republic of Korea in Seoul, claiming jurisdiction over all of Korea..
September 8, 1948
Kim Il-sung declares the formation of the Democratic People’s Republic of Korea in Pyongyang, also claiming jurisdiction over all of Korea.
From the Liberty in North Korea website