The research I've read recently puts this concern on the Japanese side. They delayed their surrender, despite atomic attacks, until after it was clear that the Russians were starting to pivot to the Pacific theater, and decided it was better to surrender to the US today than to endure a Russian invasion and occupation.
The Emperor states himself in his surrender that his decision was influenced by the display of the atomic bombs, and ultimately it was the Emperor who put the final end to the Japanese war effort.
It’s probably foolish to say the Soviets didn’t play a part in the decisions of some of the men involved but I also strongly doubt there’s a compelling argument that it was more influential than what the Americans had just shown themselves capable of doing. The Soviets were a distant threat compared to the Americans continually bombing Japan for 3 months up to that point.
> The Emperor states himself in his surrender that his decision was influenced by the display of the atomic bombs, and ultimately it was the Emperor who put the final end to the Japanese war effort.
The argument goes that the Emperor's public statements were an effort to save face in front of the country. "No, it wasn't our incompetence that created defeat, they had a Super Weapon!" The Russians could have had ground troops on Japanese territory in days, compared to weeks or months for the Americans.
