The Manchurian Strategic Offensive Operation (, lit. Manchzhurskaya Strategicheskaya Nastupatelnaya Operaciya) began on 9 August 1945, with the Soviet invasion of the Japanese puppet state of Manchukuo and was the last campaign of the Second World War and the largest of the 1945 Soviet–Japanese War which resumed hostilities between the Soviet Union and the Empire of Japan after almost six years of peace. Soviet gains on the continent were Manchukuo, Mengjiang (Inner Mongolia) and northern Korea. The Soviet entry into the war and the defeat of the Kwantung Army was a significant factor in the Japanese government's decision to surrender unconditionally, as it made apparent the USSR would no longer be willing to act as a third party in negotiating an end to hostilities on conditional terms.