To this end , Stalin and Molotov strung out the negotiations with the Japanese , giving them false hope of a Soviet-mediated peace . At the same time , in their dealings with the United States and Britain , the Soviets insisted on strict adherence to the Cairo Declaration , re-affirmed at the Yalta Conference , that the Allies would not accept separate or conditional peace with Japan . The Japanese would have to surrender unconditionally to all the Allies . To prolong the war , the Soviets opposed any attempt to weaken this requirement . This would give the Soviets time to complete the transfer of their troops from the Western Front to the Far East , and conquer Manchuria ( Manchukuo ) , Inner Mongolia ( Mengjiang ) , Korea , South Sakhalin , the Kuriles , and possibly , Hokkaidō ( starting with a landing at Rumoi )
Yalta Conference
Yalta Conference
Surrender of Japan