Not all "revisionist" history is bad. Eric Foner, who once wore this label, has written the go-to book about U.S. Reconstruction from the Civil War, for example.
Some of it is bad, though, and deserves the connotative as well as denotative label.
Ever since Gar Alperovitz wrote about the end of World War II in the Pacific, a new round of revisionist history has continued to rear its head, devoted to condemnation of the use of atomic bombs, not only on moral grounds but on pragmatic war-related grounds, too.
The themes are simple, and are, in basic:
1. The USSR's invasion of Manchuria was going to end the war soon;
2. US calculation of invasion-related casualties were overrated.
The latest? Australian journalist and historian Paul Ham, in this piece.
Let's address that first claim.
Here's Wikpedia on Hirohito's surrender speech. The first thing to note is that the USSR is nowhere mentioned by name. Here's the two key grafs:
Despite the best that has been done by everyone – the gallant fighting of the military and naval forces, the diligence and assiduity of Our servants of the State, and the devoted service of Our one hundred million people – the war situation has developed not necessarily to Japan's advantage, while the general trends of the world have all turned against her interest.
Moreover, the enemy has begun to employ a new and most cruel bomb, the power of which to do damage is, indeed, incalculable, taking the toll of many innocent lives. Should We continue to fight, not only would it result in an ultimate collapse and obliteration of the Japanese nation, but also it would lead to the total extinction of human civilization.
Tis true that the Soviet invasion of Manchuria (and the Kurile Islands, which is why the US was worried about Stalin trying to grab Hokkaido) could be included among "the general trends of the world."
But, the one element Hirohito seizes on to justify calling for surrender, and which was also part of his intervention in the Japanese war cabinet to push it to this point, is the atomic bombs.
Hirohito had no way of knowing we were "out of stock," of course. He probably figured that, just we had had three days pause between Hiroshima and Nagasaki, we were giving Japan a bit more time to reflect this time.
Even if we accept that the Soviet declaration of war was a factor, it seems clear that by itself, it wouldn't have been enough.
As for the casualties issue? From a US nationalist point, any US military casualties that were saved by each day sooner the war was ended, each day less that Japanese kamikazes attacked a blockading fleet, etc., reduced casualties.
Ditto for both the US and allies, on prisoners of war dying of starvation.
And, considering that the US, in case of a longer-term blockade, next planned to sever all connections between the home islands? Mass Japanese starvation would have resulted.
The fact that Hirohito needed to ram the surrender through his war cabinet, then get lucky enough to survive an attempted military coup that tried to block broadcast of his surrender speech underscores that the atomic bomb had effect in pushing toward surrender.
Meanwhile, at Ham's piece, one commenter is pulling red herrings out of his backside, with claims like Hirohito was afraid of a Communist revolution at home and afraid that, if the USSR gobbled up too many of his troops, he wouldn't be able to supress this.
First, Japanese troops in Manchuria/Manchukuo, as opposed to active fighting areas further south in China, were largely garrison type troops, undertrained and undersupplied as compared to fighting troops. That's part of how they got gobbled up.d
As for Communist fears? Given that the Japanese Communist Party pretty much dissolved after 1935, there's the red herring.
The issue of Japan's actual surrender being conditional is at best a red herring and at worst actually undermines Ham and his red herring commenter. If even the "most cruel bomb" would lead only to a request for a conditional surrender, the Soviet action by itself wouldn't have done that. Not that early, at least.