Question: When did the Operation that seized the territories formally claimed by  Manchukuo began
Sentence (from "Soviet invasion of Manchuria"): 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 Soviet Union would no longer be willing to act as a third party in negotiating an end to hostilities on conditional terms.
Relevant evidence: No