I agree with Norrin. [Looks up, worried that the sky may be falling . . .]

The principle of civilian control of the military is solidly entrenched in every government except a military dictatorship. Even in nondemocratic governments such as Nazi Germany or the Soviet Union, the civilian government had the last word on military action. In the case in question, the decision to drop the bomb was made by President Truman, not by a general. The decision to fund the Manhattan Project was made by President Roosevelt, not by a general (and by Congress in some fashion one supposes, although the project was so secret that it's doubtful most of Congress knew about it).

As to why we used nuclear weapons in Japan, the argument that it was necessary to forestall the casualties from an invasion of Japan has never been convincing to me, for the simple reason that no invasion of Japan was necessary. A blockade and a little patience would have brought about surrender. The Japanese were already beaten at that point and represented no military threat. Nor do I believe Truman would have used nukes merely to shorten the war's technical duration by a few months, as opposed to avoiding casualties.

The most likely reason the bomb was used had to do more with our allies than our enemies. The Soviet Union was under agreement to declare war on Japan after the surrender of Nazi Germany. Stalin kept this promise, which is how he got his hands on North Korea. At the same time, Soviet troops were occupying all of eastern Europe after driving the Germans out of same, and concern in the U.S. was already shifting from the defeated Axis to the USSR. Nuking Japan may have hastened the surrender by a month or two, but much more importantly it sent a message of power and ruthless resolve to Stalin in a language the Soviet dictator understood fluently.

In short, I believe the people of Hiroshima and Nagasaki were sacrificed on the altar, not of military victory, nor of saving American lives, but of Cold War geopolitics.