On 8 August 1945 , the Soviet Union declared war on Japan , in accordance with the agreement at the Yalta Conference , and invaded Manchukuo from outer Manchuria and Outer Mongolia . During the Soviet offensive , the Manchukuo Imperial Army , on paper a 200,000-man force , performed poorly and whole units surrendered to the Soviets without firing a single shot ; there were even cases of armed riots and mutinies against the Japanese forces . Emperor Kangde had hoped to escape to Japan to surrender to the Americans , but the Soviets captured him and eventually extradited him to the communist government in China , where the authorities had him imprisoned as a war criminal along with all other captured Manchukuo officials
Yalta Conference
Yalta Conference
Manchukuo