Japan had ruled the Korean Peninsula between 1910 and 1945. When Japan surrendered in August 1945, the 38th parallel was established as the boundary between Soviet and American occupation zones. This parallel divided the Korean peninsula roughly in the middle. In 1948, this parallel became the boundary between the Democratic People's Republic of Korea (North Korea) and the Republic of Korea (South Korea), both of which claim to be the government of the whole of Korea. On 25 June 1950, after a series of cross-border raids and gunfire from both the Northern and the Southern sides, the North Korean Army crossed the 38th parallel and invaded South Korea. This sparked United Nations Security Council Resolution 82 which called for the North to return its troops to behind the 38th parallel, commencing the Korean War with United Nations troops (mostly American) helping South Korean troops to defend South Korea.[2]
After the Armistice agreement was signed on July 27, 1953, a new line was established to separate North Korea and South Korea. This Military Demarcation Line is surrounded by a Demilitarized Zone. The demarcation line crosses the 38th parallel, from the southwest to the northeast.