Truman is dead. Roosevelt is dead. Groves is dead. Conant is dead. Oppenheimer is dead. Teller is dead. Einstein is dead. Fermi is dead. Doolittle is dead. Churchill is dead. Stalin is dead. I believe that all of the crew of the Enola Gay and Bock's Car are dead, but I don't know for certain. But I do know that damned near everyone of any consequence has had to face a Judge far more just and knowing than any human one and we who live now have to live with the decisions made then.

Refighting WW2 (or any other war) is an interesting and even fruitful exercise, but you can't change the actual historical outcome. Sure, a naval blockade could have starved Japan into submission -- perhaps, but we'll never know.

Try this: You are Harry S. Truman. Your nation has been at war for four years, there are lots of dead and wounded. Germany has surrendered, and you're turning your attention to the Pacific. The troops in Europe will go fight, but they certainly aren't enthusiastic. You're told that an invasion of Japan will bring millions of casualties, and you're also told that there's a new weapon of immense, unbelievable power. Churchill and Stalin are both aware of this weapon, and they too have troops that will be committed or are committed in the Pacific. What do you do?