At the Tehran Conference in November 1943 and the Yalta Conference in February 1945 , the Soviet Union promised to join its allies in the Pacific War within three months of the victory in Europe . Accordingly , it declared war on Japan on 9 August 1945 , three days after the USA atomic bombing of Hiroshima . By 10 August , the Red Army had begun to occupy the northern part of the Korean Peninsula
Yalta Conference
Yalta Conference
Korean War