Manchukuo was the Japanese puppet state in Manchuria invaded by Soviet forces as Japan moved toward surrender in August 1945.
Manchukuo had been established by Japan in 1932 after the occupation of Manchuria. Japan installed Puyi, the former Qing emperor of China, as its nominal ruler. In practice, Japanese authorities controlled the state and used it as a base for military operations, industry, and resource extraction.
The Soviet invasion began on August 9, 1945, as part of the Manchurian Strategic Offensive Operation. Soviet forces attacked across several fronts with large armored and mechanized formations. The offensive rapidly overwhelmed the Kwantung Army, which had once been one of Japan’s most powerful military organizations.
Manchukuo should not be confused with Mengjiang, another Japanese-backed state in Inner Mongolia. The Soviet offensive also reached areas beyond Manchukuo, including Inner Mongolia, northern Korea, southern Sakhalin, and the Kuril Islands. The campaign ended as Japan’s surrender took effect in early September.