It’s un-American that we should be a nation running around the world torturing and murdering in the name of nation building. There simply is no need for us to do that inn order for us to build a nice life here. We aren’t the third reich.
The reality is (as BobL basically said) that for over 3000 years, people who wanted to "nation build" were basically setting up empires. And the way you do that is to torture your opponents, wipe out entire villages, and take people (men, women, children) into absolute slavery (in mines, in fields, in households, etc.). If you want to subdue a population and re-construct a society into something which is more to your own liking, that's how you do it. The Assyrians knew. The Egyptians knew. The Romans knew. Hitler was basically following the old precedent.
But today, all of that stuff is frowned upon (as it should be).
So anyone (America) who tries to "nation build" without doing any of that, is just going to do a terrible job, and basically waste time, lives and treasure.
Lession: Do not "nation build".