Kuznick is an advocate of what might be negatively called an extremely "revisionist" position on the atomic bombings. This argument is not a new one — the question of whether the atomic bombs ended the war or were necessary to end the war has been debated since the 1940s, but got more steam in the late and post Cold War. The basic argument is that Japan was already defeated, and that what ended the war was that the Soviet Union invaded Manchuria.

There are some versions of this argument that are more persuasive than others. Kuznick is what I would consider to be on the far "left" side of that particular stance (with the 'orthodox' "two bombs were necessary to end the war and they did" argument somewhere on the right end of things). I think most historians of this period are somewhat more in the center of things, what J. Samuel Walker calls the "consensus" view. This position recognizes the strongest and most persuasive parts of the "orthodox" and "revisionist" arguments but also tries to get around their shortcomings.

The "orthodox" argument ignores that in some ways the US did not exhaust its options in avoiding the use of the bomb, typically ignores the Soviet component, and generally warps the "decision" to use the bomb into an overly simplistic binary choice ("bomb or invade," which pretty much locks you into "bomb"). (And the fact that the "orthodox" argument is itself a deliberate historical construction by several of the people who were involved in dropping the bomb, largely as a response to criticism, gets swept under the rug by people who advocate it.) The "revisionist" argument makes the US leaders far too prescient, ignores that one can have multiple motivations for things, and expresses far too much confidence on matters that are very hard to determine (like whether the Soviet invasion or the atomic bombings were more or less influential on the Japanese decision to surrender — they are hopelessly entangled as they happened near-simultaneously).

Anyway. Kuznick's approach isn't totally outside the bounds of good historical scholarship (Hasegawa's Racing the Enemy makes the same argument), but he has a definite "slant" to how he reads things. That doesn't make him different from other historians. But I think you'd find most historians of the subject to be a little more moderated. He is correct, though, that the simple notions of the "orthodox" version — which is what most people know and are taught — are not considered accurate by most historians. The questions being asked — were the bombs necessary? did they cause the Japanese to surrender? — are not easy to answer.

Ill repost the reply I just wrote in another thread today.

Its not a new theory, and saying its "rattling cages" implies a certain tone against history as it happened that I don't appreciate.

The Japanese were going to use the Russians as mediators to sue for peace with the Americans after they bloodied their (US forces') noses in the invasion of Kyushu, which all sides knew was happening before 1946. The Russians rebuffed the Japanese efforts to assist in that matter, with increasing coldness, until the Japanese started seeking neutral third parties like Switzerland to mediate between Japan and America.

The Japanese were well prepared, militarily, logistically, and mentally, to defend the home islands from invasion, from the Americans and the Russians if need be. They knew they couldn't stop the allies, they merely pinned their hopes on making the invasion forces suffer sufficient losses as to broker an attractive bargaining position for peace. They were confident (and in fact never recorded more than a few isolated lines of any alternative) that bloodying the invading ground forces would be Japan's final play. Their confidence was well placed; numerically, they had superior ground forces and kamikaze forces in the area they (correctly) predicted the Americans would invade. It was going to be bad.

The A Bombs changed that. The Russians declaring war did not. By the time the Russians declared war, Japan was already starting to build up forces in the Northern home islands. They weren't counting on the Russians to remain out of the coming fight.

The atomic bombings did several things that Russian declaration of war didn't. It heaped pain upon civilians on a scale that personally affected the Emperor. It gave him and those who secretly wanted immediate peace (they weren't many, but they were in influential positions; they remained nearly silent up till this point due to the very real threat of assassination) a way to surrender with at least some of Japan's dignity in tact, by pointing to the overwhelming firepower and technology arrayed against them in the form of atomic weapons. Third effect, and probably the smallest compared to the other ones I've mentioned, is that one of the major coordination areas for forces in Kyushu (the ones building up to repel the American invasion), not to mention the actual army headquarters for all forces in Kyushu, was completely destroyed by the bombing of Hiroshima.

The Russian declaration of war was a blow to their chances, but their chances of victory were already non-existant, and they had already resigned themselves to an Okinawa-esque fight of attrition.

Adding another enemy only steeled that resolve.

The atomic bombings shattered that resolve, and gave the emperor a way to surrender without a bloody invasion.

Source: Dowfall: The End of the Imperial Japanese Empire by Richard Frank

What do you make of the quote, from Curtis LeMay who was in charge of the bombing, stating in a press conference: “The war would have been over in two weeks without the Russians entering and without the atomic bomb . . . the atomic bomb had nothing to do with the end of the war at all.”