David Dean Rusk was the United States secretary of state from 1961 to 1969 under presidents John F. Kennedy and Lyndon B. Johnson, the second-longest serving Secretary of State after Cordell Hull from the Franklin Roosevelt administration. He had been a high government official in the 1940s and early 1950s, as well as the head of a leading foundation. He is cited as one of the two officers responsible for dividing the two Koreas at the 38th parallel.

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.