Which Soviet military operation began after the USSR declared war on Japan in August 1945?

The Soviet invasion of Manchuria began after the USSR declared war on Japan in August 1945.

The Soviet Union declared war on Japan on August 8, 1945, and Soviet forces began attacking Japanese positions in Manchuria shortly afterward. The campaign is also known as the Soviet–Japanese War and the Manchurian Strategic Offensive Operation.

Soviet forces attacked Japanese-controlled Manchukuo from several directions. They also advanced into areas including southern Sakhalin and the Kuril Islands. The offensive rapidly overwhelmed the Kwantung Army, which Japan had regarded as one of its major forces in northeast Asia.

The Soviet entry added a major strategic shock to Japan’s leaders, who had hoped the Soviet Union might help mediate an end to the war. Together with the atomic bombings and the worsening military situation, it accelerated the surrender process.

The campaign ended after Japan announced its surrender, although fighting and local surrender arrangements continued in some areas for a time.