This is a debate that will never go away. I figure that any attempt to evaluate the decision to use the Atomic bombs without taking the whole, long, murderous war into account is simply childish. Tens of millions of people were killed during the war. By the time August 1945 came around, the outcome may not have been in doubt but the duration and final toll was far from clear.
WRONG RIGHT Vincent Browne says the bombing of Hiroshima & Nagasaki was terrorism. Hiroshima survivor says Japanese would have fought until the bitter end. Guardian columnist says the idea bomb was necessary is now discredited. National Review columnist says that the view the war was essentially over by Aug 1945 doesn't take the Okinawa experience into account. Irish Independent says that as time has passed it's increasingly hard to justify using the Atomic bomb. The Pittsburgh Tribune-Review says recently released documents show that those who ran Japan at the time had no intention of surrendering.
I'm sure President Truman didn't like making such a decision, but I doubt he really considered it much of a choice. He wasn't a philosopher or a theologian. His role was to end the war and that's what he did. And, he was a civilian. Some of the military men might have figured that the bomb wasn't necessary, that the army & marines could do the job, but Truman knew that even the unnecessary loss of 100,000 American sons, brothers & husbands in an invasion of Japan was untenable. People may not like it, but Truman's job was to protect the United States to the best of his ability, which using the Atomic bomb did.
War is grotesque.