Here is a good stat for you to justify the use of atomic weapons. In the last year of the war in the Asia Pacific theater, Japanese troops were responsible for 250,000 non combatant (civilian) deaths a month. This stat is brought up very early in the latest installment of Dan Carlan's Hardcore History. If you are causing the death of that many people per month and they are not even at the mainland yet it would only get worse. Using atomic weapons saved civilian lives too. 140,000 died in Hiroshima, and 74,000 in Nagasaki. And it is tragic that so many died from a single bomb, but still less than what the Japanese were killing per month.