Korean War Timeline

August 15, 1945

Japan surrenders, ending World War II. That night, U.S. Army officers Dean Rusk and Charles Bonesteel consult a National Geographic map of Asia to determine the postwar dividing line between Soviet and U.S. zones of control in Korea. Neither man is an expert on the country, and, failing to find any obvious natural barrier between the North and the South, they select the 38th parallel, a border that was tentatively proposed at the Potsdam Conference. This division places the capital city of Seoulin the American zone but just 35 miles south of the dividing line.

August 15, 1948

• The Republic of Korea (South Korea) is established. Less than a month later the Democratic People’s Republic of Korea (North Korea) is established.

January 12, 1950

• In a speech to the National Press Club, U.S. Secretary of State Dean Acheson outlines a U.S. Pacific defense posture that includes Japan and the Philippines but does not explicitly include Korea. In fact, he states that, “so far as the military security of other areas in the Pacific is concerned, it must be clear that no person can guarantee these areas against military attack.”

January 17, 1950

• North Korean leader Kim Il-Sung proposes the “liberation” of South Korea to Soviet officials. Weeks of telegram exchanges between Beijing, Moscow, and P'yŏngyang follow, and by early spring Kim has secured assurances of support for the invasion from Soviet premier Joseph Stalin and Chinese leader Mao Zedong.