The Soviet invasion of Manchuria, or the Manchurian Strategic Offensive Operation (, lit. Manchzhurskaya Strategicheskaya Nastupatelnaya Operaciya) as the Soviet named it, began on 9 August 1945 with the Soviet invasion of the Japanese puppet state of Manchukuo and was the largest campaign of the 1945 Soviet–Japanese War which resumed hostilities between Soviet Union and the Empire of Japan after more than 4 years of peace. Soviets gains on the continent were Manchukuo, Mengjiang (Inner Mongolia) and northern Korean Peninsula. The rapid defeat of Japan's Kwantung Army was a very significant factor in the Japanese surrender and the end of World War II, as Japan realized the Russians were willing and able to take the cost of invasion of its Home Islands, after their rapid conquest of Manchuria and southern Sakhalin.