There are still people who come to Hiroshima and Nagasaki to honor not the Japanese victims but their American relatives who were spared the task of invading mainland Japan. They may come to also honor the victims who died there, but they still see the atomic bombings as justified attacks against an aggressor, as attacks which led to fewer lives being lost on both sides of the conflict. Blame ultimately lies with the aggressor, in this view. This belief persists in spite of the large amount of historical research that has been done since 1945 which demolishes the argument that the bombs were necessary to end the war and that they were the essential cause of the Japanese decision to surrender.
It has been well demonstrated that the Japanese were no longer able to wage war and they were starving for food and fuel. A negotiated surrender was possible, especially on terms that required only that the emperor be retained as a symbolic head of the Japanese people. This condition was rejected in favor of pursuing an unconditional surrender, then after the surrender, the American occupying forces decided after all that Japan would be easier to manage if the emperor were kept in place. That fact alone should be enough to put an end to the assertion that the bombs were necessary to end the war, but then there is the additional fact that the Soviet declaration of war on August 9, 1945 made much more of an impression on the decision-makers in Tokyo. Over the next few days until the surrender on August 15, the bombs hardly registered in cabinet discussions as an issue to be worried about. It was just two other cities that had been bombed. Like other ruined cities all over Japan, they were regarded as acceptable sacrifices.
What bothers me most about the people who still hold onto this discredited view is the fact that they are often the same people who say very solemnly that atomic weapons must never be used again. We know now, apparently, but we didn’t know then. On the contrary, the nature of the new weapons was pretty well understood in 1945 in terms of the damage they could do with heat, blast and radiation, and everyone involved in the Manhattan Project understood what the effects would be on the nature of war and international relations. It was known that these new weapons would launch a horrific arms race. It was known that there would soon be much larger and deadlier hydrogen bombs. It was known that these weapons might put human life back in the Stone Age. Yet still it was decided that the situation was exceptional. America was faced with an implacable aggressor that had to be stopped, but it wanted to achieve its goals at minimal cost of American lives—an attitude that some of the highest officers serving at the time found dishonorable and also an unnecessary concern because, as mentioned above, they knew that Japan would soon have to surrender on terms favorable to America. The atomic bombs were a distraction, a billion-dollar bureaucratic juggernaut that rolled to its conclusion because no one powerful enough to stop it stood in its way.
I don’t intend to thoroughly rehash this argument that has been covered fully in other sources , , , , but I just mention what should be an obvious conclusion. If you think atomic bombs should never again be used in war, then you must also accept that they should not have been used in 1945. There is no reason to believe that circumstances similar to those of 1945 could not arise again: an aggressor starts a war–and the perception of who is the aggressor may be very subjective–but those who say it is an aggressor decide it must be stopped. However, as the conflict drags on and takes an unacceptable toll, the side trying to stop the aggressor becomes impatient and decides to just drop a nuke and be done with it. Most people today would say this should never happen, but it is exactly what happened in 1945. The only difference is that now we know that the world bristles with 15,000 atomic and hydrogen bombs and we fear an uncontrollable escalation that would destroy the world. In other words, next time it would be a fair fight against enemies who could retaliate with the same sort of weapons. The reasons for justifying restraint now but not then are thus practical and selfish, not moral. Those who still justify Hiroshima and Nagasaki have a different attitude about the present or future use of nuclear weapons because they fear the repercussions on themselves, but disregard the violence that would be inflicted on the first target–that aggressor who had it coming, who had to be stopped.
If a nuclear weapon is ever used deliberately again, it’s a sure thing that the perpetrators will claim it was justified, just as they did in 1945: "They had to be stopped. We hoped it would save lives and shorten the war. Our intentions were good."
Hiroshima: Why the Bomb Was Dropped (1995 documentary)
 Gar Alperovitz, “Nuclear Attack on Japan Was Opposed by American Military Leadership,” Truth-out.org, January 14, 2014.
 Tsuyoshi Hasegawa, Racing the Enemy: Stalin, Truman, and the Surrender of Japan (Belknap, 2006).