Is it legal for US residents to trade Bitcoin with people in sanctioned countries?

So, I'm curious about the legality of US residents trading crypto, like Bitcoin, with regular folks from countries the US has sanctions against. I've been searching for a clear answer but haven't found one. If anyone here has legal insights or can share some relevant legal sources, that'd be awesome. Thanks!

Afaik there's a term for sending money abroad to family but I can't remember it's name. My assumption would be it's the same as standard currency. If you can transfer via PayPal, western union or a bank account then you should be able to do it with bitcoin. If not, how are the irs going to know about it? Are you planning to transfer large amounts as this could be where a dex might be useful if they'd want to break the link between sending to a sanctioned country from theirs.

Remittances? But that's standard fiat though? Unless you declare it, then IRS wouldn't know in the beginning, If you can't find any answers then you should consider sending money from US to a sanctioned nation is illegal and it's potential consequences.

In some part of United states,we can easily transfer the bitcoin.But in some states,their the flow of bitcoin had been lower than a as usual one.The flow of bitcoin in US was the source of Bitcoin price increase for a sudden pump and sudden dump.We can't predict with a accurate percentage.

I don't know what you mean by "cryptocurrency exchanges", but this might answer your question:

I can't find any specific examples, but according to this website: P2P shouldn't be a problem, as odolvlobo shared, but it could still certainly be seen as a method of money laundering. I don't think there will be issues with small amounts, but I would still strongly discourage it unless both parties know how to cover their tracks.

Thank you everyone for your answers.

International sanctions are imposed against the state, legal entities or officials of this state, and not against citizens.  Therefore, I believe that it is completely legal to send payments in cryptocurrency or in ordinary currency to citizens of a country against which US sanctions have been imposed.