USA dropped the first atomic bomb to reduce the loss of american soldiers. And they dropped papers there everyday, one week from the drop, to the drop, there it stood on several languages that they were going to drop the atomic bomb there. They used Hiroshima as a statement, why Japan should surrender. Many japanese survived thanks to USA anyway. USA dropped flyers for a week before they dropped the bomb saying that they would drop an none-tested heavy air-to-ground bomb there, and that the people who lived there should move out from there (They did the same thing before they bombed Nagasaki). So it's not only USA's fault, even if some people think so. But I can be wrong, maybe USA got wrong. But the truth is that the inventors of the atomic bomb was not from USA. They were from German and so on. If Japan would be a good place to live, German scientist would have moved over to Japan, and Japan would have been the one, with the first atomic bomb. It's the same problem as today, the middle east got their massdestruction weapons because after the Sovjet union broke apart, russian scientists couldn't get a job there they got payed. But people with a lot of oil money could pay their living with fat checks and so they moved to the middle east and build atomic bombs for them.
But remember that Japan was the first to attack in Peark Harbor. But the ironic about that attack is, that the air-to-sea missiles were way better then people thought, and if USA met Japan on the sea, the loss for America would been much bigger.
The Royal Navy met Japan after the Pearl Harbor attack. The Japans had the same type of airplanes and carrier, and the britains ships were a much better type than the one USA got. The ships Great Britain got was much more effective against airplanes but they lost all their brand new ships.
If USA would have met these Japanese airplanes and carriers with their much older ships, they would loss many more ships, than they did in Pearl Harbor during the attack.
Even if USA's ships wasn't ready for battle, they acctually only lost
one ship. In a combat on the ocean, they would have fought to the last man. And the last men would been japanese.