>Japan's decision to surrender in Aug'45 was based on when the Japanese knew then, not on what historians know now.
Nobody is saying anything different.
>...And several previous Japanese conclusions of "the USSR will not be able to do X" had proven catastrophically wrong. For example …
The Japanese had already moved all of their experienced troops from Manchuria before the invasion. They were surprised that the USSR would break the Soviet–Japanese Neutrality Pact, but the defense of the home islands was their main concern at that point.
As your source says:
>...The Soviet entry into this theater of the war and the defeat of the Kwantung Army were significant factors in the Japanese government's decision to surrender unconditionally on 15 August, as it became apparent that the Soviet Union had no intention of acting as a third party in negotiating an end of the war on conditional terms.
The Japanese knew the USSR was not a threat to the main islands and the USSR knew they would likely fail if they tried to invade Hokkaido. The Japanese had hopes that the USSR would be willing to negotiate with the Allies on their behalf, but once the Soviets declared war was, they knew that would not happen.
Nobody is saying anything different.
>...And several previous Japanese conclusions of "the USSR will not be able to do X" had proven catastrophically wrong. For example …
The Japanese had already moved all of their experienced troops from Manchuria before the invasion. They were surprised that the USSR would break the Soviet–Japanese Neutrality Pact, but the defense of the home islands was their main concern at that point.
As your source says:
>...The Soviet entry into this theater of the war and the defeat of the Kwantung Army were significant factors in the Japanese government's decision to surrender unconditionally on 15 August, as it became apparent that the Soviet Union had no intention of acting as a third party in negotiating an end of the war on conditional terms.
The Japanese knew the USSR was not a threat to the main islands and the USSR knew they would likely fail if they tried to invade Hokkaido. The Japanese had hopes that the USSR would be willing to negotiate with the Allies on their behalf, but once the Soviets declared war was, they knew that would not happen.