Or do you advocate just stealing the property of countries that don't align with what you want them to do?
I don't advocate stealing it, but that's not the same thing as returning it. There's lots of complications to the issue, that the simple idea of "returning" it ignores. We have all kinds of concepts of escrow in our legal world that could have been used. Heck, the money could have been spent on behalf of the Iranian people by us, or like I said used to recompense victims of Iranian hostility.
I don't see that if you borrowed $5k from your grandmother that after she passes, "returning" to your cousin who's addicted to Herion or is looking for $5k to pay a may to kill his wife is a good thing. Holding it until he grows our of it? Maybe, using it to pay for his treatment, maybe? Handing it over being morally right - don't see it (note, legally right is a different context, but it's less applicable in international relations).
I can not separate knowledge of what Iran would use (and did use) the money to support with a "moral" position that we had to give it back.
How shall we assess that harm that the US has caused?
How about on a net basis. I'm confident that we've acted overall, and in many local cases, on a net positive basis. Should we hold ourselves to an even higher standard? Of course. But we shouldn't pretend we've been a force of evil, when we haven't.
