At the Yalta Conference ( February 1945 ) , amongst other things , Stalin secured from Roosevelt the promise of Stalin 's Far Eastern territorial desires , in return agreeing to enter the Pacific War within two or three months of the defeat of Germany . By the middle of March 1945 , things were not going well in the Pacific for the Japanese , and they withdrew their elite troops from Manchuria to support actions in the Pacific . Meanwhile , the Soviets continued their Far Eastern buildup . The Soviets had decided that they did not wish to renew the Neutrality Pact . The terms of the Neutrality Pact required that 12 months before its expiry , the Soviets must advise the Japanese of this , so on 5 April 1945 they informed the Japanese that they did not wish to renew the treaty . This caused the Japanese considerable concern , but the Soviets went to great efforts to assure the Japanese that the treaty would still be in force for another twelve months , and that the Japanese had nothing to worry about
Yalta Conference
Yalta Conference
Soviet–Japanese War