The nuking of Hiroshima and Nagasaki were not "vengeful" actions, but sound strategic decisions that ended up saving countless American AND Japanese lives.
My dad would have been one of the sailors driving a landing barge in the first wave of the invasion of Japan. My understanding is that there is about an 80% chance he would have died in that event.
I am very glad that the atomic bomb gave me a much better chance for life, as well as saving the lives of the more than a million other Americans and other millions of Japanese.