Which Soviet military campaign began on 9 August 1945 during Japan's final days of World War II?

The Soviet invasion of Manchuria began on 9 August 1945 during Japan's final days of World War II. Soviet forces attacked Japanese-held Manchuria from multiple directions in a major campaign against the Kwantung Army.

The Soviet Union declared war on Japan on 8 August, with the invasion beginning shortly after midnight in the relevant regional time. The offensive advanced from the east, west, and north, overwhelming Japanese positions across the region.

The campaign was launched three months after Germany's surrender, fulfilling a commitment associated with the Tehran and Yalta agreements. Soviet forces also moved into areas including Inner Mongolia, southern Sakhalin, and northern Korea during the wider Soviet-Japanese War.

Japan's leadership faced this offensive alongside the atomic bombings of Hiroshima and Nagasaki. Historians debate the relative importance of these events, but the Soviet entry clearly removed Japan's hope that Moscow might mediate a favorable settlement.