Soviet forces invaded Manchuria when they entered the war against Japan in August 1945.
Manchuria, in northeastern China, was then largely controlled by Japan through the puppet state of Manchukuo. The Japanese Kwantung Army had occupied the region since the early 1930s, making it one of the most important areas of Japan’s continental empire.
The Soviet invasion began shortly after midnight on August 9, 1945, following the Soviet declaration of war. The offensive involved coordinated attacks from the east, west, and north. Soviet troops rapidly overwhelmed Japanese defenses and captured major cities, transport routes, and strategic positions.
Manchuria was not the only area affected. Soviet forces also attacked Japanese positions in Korea, southern Sakhalin, and the Kuril Islands. However, Manchuria was the principal theater of the Soviet campaign. It is sometimes confused with the Soviet assault on Sakhalin or the later fighting in the Kurils, which were separate operations within the broader Soviet–Japanese War.