American soldiers don't intentionally kill noncombatants. If they do, they get prosecuted like any other criminal. No comparison.
Hiroshima and Nagasaki were intentional and more civilians died than combatants by the thousands. Of course you have Dresden and hundreds of other towns. My mother`s town Boeblingen was decimated by air attack and ground. American soldiers shot and killed two of her great nieces and they were just children. She was named after one of them. The soldiers were never prosecuted or even heard of.
Then you have Vietnam now Iraq where over a million have died according to Door to Door ground estimates conducted by Johns Hopkins University, the most thorough and accurate casualty count ever performed on any single nation at war.
Your rosy view of Americans prosecuting a "clean" war is far from the truth.