"I've won, but at what cost?"

Why did Oppenheimer feel guilty about the bombings of Hiroshima and Nagasaki? Japan started it, and Oppenheimer helped the United States finish it. If the atomic bomb had not been invented, the United States would have had to perform a full-scale D-Day style invasion of Japan with ground troops that would have cost at least two million lives on both sides (assuming it worked). The bombings of Hiroshima and Nagasaki killed 250,000 people at most.

You cannot demand others respect yiu. You must work to earn their respect. And there are three sure-fire ways you can earn the respect of other people:
1. Accomplish what they believe to be impossible.
2. Become their worst nightmare.
3. Beat them at their own game.

The bombings of Hiroshima and Nagasaki earned the respect of Japan by doing all three at once. I'm sure the Japanese never in their wildest dreams thought a single plane dropping a single bomb could cause so much damage .
We Americans scared the Japanese straight and taught them the error of their ways. So they surrendered and they never messed with us again. People don't mess with you when they're afraid of you.

I was mostly referring to the test bombing.

I personally think that no matter the greatness of the outcome, we humans are in no position to trade innocent lives for innocent lives. The bombing on Japan served the army who attacked us well, but it also killed innocent civilians, and we humans are in no position to trade innocent lives, even if it's a good trade. Oppenheimer has every right to feel at least slightly guilty on what he enabled the government to do, but I was mostly talking about the test bombing.

Yes I agree, that was a very tactical and successful method, weither it was moral or not.

"I am become death, the destroyer of worlds" - J. Robert Oppenheimer