No Japanese guilt neccessary?
("Was Hiroshima Necessary? Why the Atomic Bombings Could Have Been Avoided", Mark Weber, The Journal of Historical Review, May-June 1997 (Vol. 16, No. 3), pages 4-11., Institute for Historical Review)
President Truman steadfastly defended his use of the atomic bomb, claiming that it "saved millions of lives" by bringing the war to a quick end. Justifying his decision, he went so far as to declare: "The world will note that the first atomic bomb was dropped on Hiroshima, a military base. That was because we wished in this first attack to avoid, insofar as possible, the killing of civilians."
This was a preposterous statement. In fact, almost all of the victims were civilians, and the United States Strategic Bombing Survey (issued in 1946) stated in its official report: "Hiroshima and Nagasaki were chosen as targets because of their concentration of activities and population."
If the atomic bomb was dropped to impress the Japanese leaders with the immense destructive power of a new weapon, this could have been accomplished by deploying it on an isolated military base. It was not necessary to destroy a large city. And whatever the justification for the Hiroshima blast, it is much more difficult to defend the second bombing of Nagasaki.
("Release when Ready", David Irving, 1995, Focal Point)
On July 8, the Department learned that the Japanese military attaché at Stockholm had told Prince Bernadotte over dinner that the Emperor Hirohito would ask Sweden's King Gustav to contact the Allies when the right time came, and that he had stated only one Japanese condition of surrendering: namely, that the Emperor himself remain in office. (This term was subsequently adopted by the Allies).
Tokyo's urgent telegrams, attempting to surrender, continued for the next two weeks. The American government many years ago released these intercepts, buried among half a million others, to the National Archives in Washington, DC.
Although the British codebreakers obtained the whole series, the British government has only recently confessed to their existence and even then -- in a fit of limited openness -- recently only two of those telegrams revealing Japan's surrender attempts, those dated July 24 and 25, 1945, to the Public Record Office, where they can be found in Class HW.1. The fact that Whitehall was aware of Japanese surrender attempts ever since July 13 is still concealed from British researchers.
In my view the billion-dollar "Manhattan Project" had gathered a momentum of its own. It was unstoppable. Too many people had an interest in seeing it used, particularly the statesmen who had pushed it and the technicians who had built it. The latter wanted it used on an as yet undamaged target, to calibrate its infernal power against real flesh and blood, against buildings and bridges.
TLDR: No, the atomic bombs were not necessary. Japan was ready to surrender on the same terms before the bombing but the news were censored by the Allies, and the bombs only targeted civilians, for no other reason than testing the results of the Manhattan Project and giving a warning to the Soviets.