As the USA introduced a bill to try & sop Iran from using its own crypto, the question is not if it will work.
Perhaps not even if the USA has the right to stop aother Nation state doing so.
The bigger question is will it work, or can it work.
It seems that the SWIFT banking is being bypassed in so many ways, eg XRP, so stopping payments via SWIFT has little effect.
So with the decentralised nature of cryptos, other than tracking individuals who use a particular coin, how could the new laws be applied.