The Soviet invasion of Manchuria began on 8 August 1945 , with an assault on the Japanese puppet states of Manchukuo and neighbouring Mengjiang ; the greater offensive would eventually include northern Korea , southern Sakhalin , and the Kuril Islands . Apart from the Battles of Khalkhin Gol , it marked the only military action of the Soviet Union against Imperial Japan ; at the Yalta Conference , it had agreed to Allied pleas to terminate the neutrality pact with Japan and enter the Second World War 's Pacific theatre within three months after the end of the war in Europe . While not a part of the Eastern Front operations , it is included here because the commanders and much of the forces used by the Red Army came from the European Theatre of operations and benefited from the experience gained there . In many ways this was a ' perfect ' operation , delivered with the skill gained during the bitter fighting with the Wehrmacht and Luftwaffe over four years
Yalta Conference
Yalta Conference
Eastern Front (World War II)