Manchukuo was the Japanese puppet state in Manchuria overthrown during the Soviet offensive of August 1945.
Japan established Manchukuo in 1932 after the Japanese occupation of Manchuria. Although presented as an independent state, it was controlled by Japan and served as a base for military operations and economic exploitation. The last Qing emperor, Puyi, was installed as its nominal ruler.
The Soviet Union declared war on Japan on August 8, 1945, and invaded Manchuria just after midnight on August 9. Soviet forces attacked across several fronts, rapidly overwhelming the Japanese Kwantung Army and dismantling Japanese control in Manchukuo.
The offensive intensified Japan’s strategic crisis. Japanese leaders could no longer rely on Soviet neutrality or hope that Moscow would mediate a conditional peace. Manchukuo should not be confused with Mengjiang, another Japanese-backed state in Inner Mongolia, which was also affected by the Soviet campaign.