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.

South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern part of the Korean Peninsula and borders North Korea along the Korean Demilitarized Zone; though it also claims the land border with China and Russia. The country's western border is formed by the Yellow Sea, while its eastern border is defined by the Sea of Japan. South Korea claims to be the sole legitimate government of the entire peninsula and adjacent islands. It has a population of 51.96 million, of which roughly half live in the Seoul Capital Area, the ninth most populous metropolitan area in the world. Other major cities include Incheon, Busan, and Daegu.