You are referring to things that were agreed to in international treaties and trade negotiations - again these sorts of things are super common

No, I'm referring to unilateral measures the US takes to force countries that do not themselves have sanctions against Iran and Cubs to stop trading with those countries.

These secondary sanctions are not based on international treaties and trade negotiations. They're based on levers of power that the US possesses and exploits, much to the chagrin of foreign countries. They are also not common. There's no other country that comes close to imposing its trade policy on the rest of the world in this manner.

> These secondary sanctions are not based on international treaties and trade negotiations

You clearly have no idea what you’re talking about - these things don’t just happen overnight cause the US says so.

Sanctions in this case have been discussed and formalized by multiple groups and organizations including OECD, FATF and the UN Security Council.