The Soviet Union invaded Japanese-held Manchuria on August 9, 1945.
The Red Army began its large-scale offensive against Manchukuo, Japan’s puppet state in Manchuria, shortly after the Soviet declaration of war on Japan. Soviet forces attacked from several directions, including from the east, west, and north. The operation rapidly overwhelmed the Japanese Kwantung Army and reshaped the final weeks of the war in Asia.
The invasion began between the American atomic bombings of Hiroshima on August 6 and Nagasaki on August 9. Historians continue to debate the relative importance of the Soviet attack and the atomic bombings in Japan’s decision to surrender, but both events dramatically reduced Japan’s remaining strategic options.
The Kwantung Army officially surrendered on August 16, although fighting continued in some areas until the formal Japanese surrender on September 2. Soviet forces also advanced into Korea, southern Sakhalin, and the Kuril Islands during the final phase of the conflict.