I address more in the other comment. I was more trying to head off the oliver stone, "it was exclusively the Soviets", which was the original post. The article is okay, but spends too much time on the mental faculties of those involved.

No, I have not forgot the firebombings. They should have weighed the firebombings as the same. But they didn't. Some of it was that it was novel and a single bomb. New capabilities seem to leave an impression, such as V2's for the ability to hit a target without warning, even though they were cost ineffective. But, they were not grasping their predicament.

But take the Soviet case to it's conclusion, and that the bombs had no impact on whether they thought the war should be continued. They could have waited more if it was just the soviets, as all the stated Soviet plans do not involve Honshu. You likely had a couple months at the minimum, even if the soviets rushed. And it's not like I hear any worries of communism in anything, Japan had a pact with them and tried to use them as a third party. So why not try to negotiate openly with the US/GB/China/Soviets then? Half their cabinet thought to try even after everything. No, hirohito, thought the US was going to bomb them to bits in the interim, whether by firebomb or atom bomb, and the offer was only going to get worse. So they ended it.

This isn't to say that maybe the atom bombs weren't needed to come to that position, as the previous bombings might have been enough. Or maybe a few weeks of waiting would have been enough. I ponder if their had been no bombings of any kind, per the rules of war, would Japan have surrendered given the Soviet involvement. I would guess no, considering the margin given and the longevity of such an event creating a way to rationalize out, but still something to think about.