Which is why we dropped the bombs in Japan. Russia entered into a war with Japan after Germany fell, and their invasion of Japanese colonial territories was swift and decisive. Several historians have found evidence that it was this decisive victory by Russia that pushed Japan to accept surrender. There was a deal being brokered by the United States and Russia at the same time plans were being forged to drop the bombs. The deal would have left Japan split, with one side being under the jurisdiction of Russia while the other being under the jurisdiction of the US. The bombs ended up being the plan, and dropping them was effectively the same as having boots on the ground. The plan with Russia was dismissed, and all surrender terms were dictated by the US as a result.
That's my understanding, anyway. I could have some of those facts wrong, so let me know if they are.