<P> The Soviet -- Japanese War ( Russian : Советско - японская война ; Japanese : ソ連 対日 参戦 , `` Soviet Union entry into war against Japan '' ) was a military conflict within the Second World War beginning soon after midnight on August 9 , 1945 , with the Soviet invasion of the Japanese puppet state of Manchukuo . The Soviets and Mongolians terminated Japanese control of Manchukuo , Mengjiang ( Inner Mongolia ) , northern Korea , Karafuto , and the Chishima Islands . The defeat of Japan 's Kwantung Army helped in the Japanese surrender and the termination of World War II . The Soviet entry into the war was a significant factor in the Japanese government 's decision to surrender unconditionally , as it made apparent the Soviet Union would no longer be willing to act as a third party in negotiating an end to hostilities on conditional terms . </P>
<P> The Soviet -- Japanese War ( Russian : Советско - японская война ; Japanese : ソ連 対日 参戦 , `` Soviet Union entry into war against Japan '' ) was a military conflict within the Second World War beginning soon after midnight on August 9 , 1945 , with the Soviet invasion of the Japanese puppet state of Manchukuo . The Soviets and Mongolians terminated Japanese control of Manchukuo , Mengjiang ( Inner Mongolia ) , northern Korea , Karafuto , and the Chishima Islands . The defeat of Japan 's Kwantung Army helped in the Japanese surrender and the termination of World War II . The Soviet entry into the war was a significant factor in the Japanese government 's decision to surrender unconditionally , as it made apparent the Soviet Union would no longer be willing to act as a third party in negotiating an end to hostilities on conditional terms . </P>
when did the soviet union declared war on japan and invade manchuria
when did the soviet union declared war on japan and invade manchuria
August 9 , 1945
August 9 , 1945