You may believe whatever you wish about the propriety of dropping the Atomic bomb on Hiroshima: Maybe it shortened the war. Maybe it saved American lives. Maybe. We might honestly--and honorably--disagree on the matter.
However the nuclear test over Nagasaki three days later was of another order of reality entirely. It was a war crime, and relegated the USofA into exactly the same class of criminality-against-humanity as the Japanese for the rape of Nanjing or the Nazis for the massacres at Baba Yar in the Ukraine (the Issei/Nissei camps had already too closely mirrored the Nazi social control model for comfort.)