The division of Korea began on August 15, 1945 when the official announcement of the surrender of Japan was released, thus ending the Pacific Theater of World War II. During the war, the Allied leaders had already been considering the question of Korea's future following Japan's eventual surrender in the war. The leaders reached an understanding that Korea would be liberated from Japan but would be placed under an international trusteeship until the Koreans would be deemed ready for self-rule. In the last days of the war, the United States proposed dividing the Korean peninsula into two occupation zones with the 38th parallel as the dividing line. The Soviets accepted their proposal and agreed to divide Korea.

Korea is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, now known as the Korean Demilitarized Zone. In 1948, two states declared independence, both claiming sovereignty over all of Korea: South Korea comprising its southern half and North Korea comprising its northern half. The region consists of the Korean Peninsula, Jeju Island, and minor islands near the peninsula. The peninsula is bordered by China to the north and Russia to the northeast, across the Amnok and Duman rivers. It is separated from Japan to the southeast by the Korea Strait.