At the Cairo Conference in November 1943 , in the middle of World War Two , Franklin D. Roosevelt , Winston Churchill and Chiang Kai-shek agreed that Japan should lose all the territories it had conquered by force . At the end of the conference , the three powers declared that they were , " mindful of the enslavement of the people of Korea , ... determined that in due course Korea shall become free and independent . " Roosevelt floated the idea of a trusteeship over Korea , but did not obtain agreement from the other powers . Roosevelt raised the idea with Joseph Stalin at the Tehran Conference in November 1943 and the Yalta Conference in February 1945 . Stalin did not disagree , but advocated that the period of trusteeship be short
Yalta Conference
Yalta Conference
Division of Korea