Which country declared war on Japan on August 8, 1945, accelerating Japan’s surrender crisis?

The Soviet Union declared war on Japan on August 8, 1945, accelerating Japan’s surrender crisis.

Soviet Foreign Minister Vyacheslav Molotov informed the Japanese ambassador in Moscow that the Soviet Union was at war with Japan. The declaration took effect on August 9 Moscow time, and Soviet forces soon launched a large offensive against Japanese forces in Manchuria.

The Soviet move shattered the Soviet-Japanese Neutrality Pact and removed Tokyo’s hope that Moscow might mediate between Japan and the Western Allies. It also opened a major front in Japanese-occupied territory at the same time that the United States had just used an atomic bomb against Hiroshima and was preparing for further action.

Japan’s leaders faced a rapidly worsening strategic position. On August 15, Emperor Hirohito announced acceptance of the Potsdam Declaration. The Soviet campaign continued after the announcement in several areas, including southern Sakhalin and the Kuril Islands.