UNCLOS has specific enforcement mechanisms behind it. I don’t know enough detail to know what they are, but yes, it’s founded on an international treaty. My point was Iran wasn’t doing it out of the goodness of their hearts, but because they got something in return: on UNCLOS specifically they get free passage for their own ships in others’ territorial waters. More broadly, they get the stability of the post-WWII international order.

The US has turned its back on that international order by attacking Iran. Therefore the incentive for Iran to participate in that order has greatly diminished.

If all international treaties are “playing nice”, then fine, they were playing nice. I prefer to see them as a mutually beneficial exchange. We’re getting dangerously close to “laws are just threats” territory though, and I think that moves us away from a conversation whose definitions are useful for dialogue.