What military campaign did Soviet forces launch against Japan on 9 August 1945?

Soviet forces launched the Soviet invasion of Manchuria against Japan on 9 August 1945.

The operation began when the Soviet Union declared war on Japan and attacked Japanese forces in Manchuria, then controlled by the Japanese puppet state of Manchukuo. Soviet troops advanced from several directions, including the Soviet Far East, Mongolia, and the region near the Amur River.

The timing was critical. The attack came between the atomic bombings of Hiroshima on 6 August and Nagasaki on 9 August. Japan’s leaders therefore confronted both the expanding Soviet offensive and the continuing American air campaign while debating surrender.

The campaign is also called the Soviet-Japanese War of 1945. Soviet forces rapidly defeated the Kwantung Army and captured large areas in Manchuria, northern Korea, southern Sakhalin, and the Kuril Islands. Japan’s surrender announcement followed on 15 August, although fighting and regional surrender arrangements continued afterward.