The sanctions didn't start yesterday, but the Treasury Department has been slowly ramping up its pressure on exchanges ever since 2017. A formal endorsement of mining by Iran suggests there will be increased Iranian capital flow into mining. Between that and the fact that
Iranian officials have repeatedly said cryptocurrencies can be used to thwart sanctions, it makes sense that US officials are watching closely. The fact is that P2P markets, DEXs, and non-KYC exchanges could theoretically allow circumvention of sanctions.
the sanctions didn't start in 2017 either they started back in 1979 just as the revolution occurred in Iran and have been only increasing ever since. my point was that if US decided to do anything to exchanges in the name of Iran and sanctions,... they would be lying their asses off since Iranians never used any of these exchanges they have access to put pressure on in first place.
any other method they were using (DEX, P2P, certain exchanges,...) have been and will remain out of their jurisdiction and reach.
Before 2017, in the eyes of the Treasury Department, cryptocurrency wasn't relevant to sanctions enforcement because the market was so tiny. That is obviously changing as Bitcoin becomes more and more valuable. And Iranians
were allowed on most exchanges before that time. That's why there was a big scandal when Bittrex disabled the accounts of all Iranians and confiscated their funds. See these threads:
https://bitcointalk.org/index.php?topic=2342458.0;allhttps://bitcointalk.org/index.php?topic=2279516.0;allFrom 2017 on, we've seen many exchanges add TOS prohibiting regions based on OFAC sanctions. This is because OFAC wasn't applying any pressure before then. Now they are.