There’s no sound moral principle anywhere that justifies the targeting of civilian populations in combat. That has nothing to do with the two atomic bombs themselves, either. As another poster pointed out on this thread, the U.S. had already crossed the Rubicon on that question long before August of 1945.
By that point in time the Japanese government had mobilized the entire population to participate in the defense of the home islands, using farm implements if necessary. Houses had been converted into arms factories. Furthermore, warnings were issued prior to the bombing for populations to evacuate major cities.
In addition, both cities were legitimate military targets as they housed both military factories and large army groups.
Your arguments are simplistic, childish, and predicated on assumptions that don’t stand up to factual analysis or middle-school logic.