What did the Soviet Union issue against Japan on August 8, 1945?

The Soviet Union issued a declaration of war against Japan on August 8, 1945.

The Soviet government informed Japan that the Soviet-Japanese Neutrality Pact would no longer govern relations and that the USSR would enter the war. Soviet forces began invading Japanese-held territory in Manchuria shortly after midnight on August 9, local time. The offensive also reached Korea, southern Sakhalin, and the Kuril Islands.

The declaration followed a commitment Stalin had made to the United States and Britain to enter the Pacific war after Germany’s defeat. Japan’s leaders had hoped the Soviet Union might mediate a negotiated peace, so the Soviet attack sharply changed the strategic situation.

The Soviet declaration came between the atomic bombings of Hiroshima on August 6 and Nagasaki on August 9. Historians continue to debate the relative weight of the Soviet entry and the atomic bombings in Japan’s decision to surrender, but the timing of the Soviet action is firmly established.