What was the codename for the Soviet invasion of Japanese-held Manchuria in August 1945?

The codename commonly used for the Soviet invasion of Japanese-held Manchuria in August 1945 was Operation August Storm.

The campaign began on August 9, 1945, when Soviet forces attacked Japanese positions in Manchuria, Inner Mongolia, and northern Korea. Its formal Soviet name was the Manchurian Strategic Offensive Operation. The offensive involved multiple Soviet fronts and Mongolian forces against the Japanese Kwantung Army and Japan's puppet states in the region.

The timing was crucial. The Soviet Union declared war on Japan late on August 8, fulfilling a commitment made at the Yalta Conference to enter the Pacific War within three months of Germany's defeat. The invasion began shortly after midnight on August 9, between the atomic bombings of Hiroshima and Nagasaki.

Japan's leaders had hoped the Soviet Union might mediate a conditional peace with the Western Allies. Soviet entry destroyed that diplomatic hope and created a new military crisis. Historians continue to debate the relative weight of the Soviet invasion and the atomic bombings in Japan's decision to surrender, but both events sharply affected the final days of the war.

Japanese forces in Manchuria formally surrendered on August 16, though fighting continued in some areas until September.