These sanctions apply to trade with the U.S.
The U.S. has no legal or moral right to use military means constrain trade among other nations that are not at war with the U.S.
You are quite wrong.
Our existing sanctions on these countries extend to all nations. There is a series of US and international laws that combine to make such Sanctions legal.
Remember the Cuban Embargo? We let that go due to lack of will, but it is similar.
I dont know why youd cite the Cuban embargo to support your point. It actually reinforces MY point. Even at the height of the embargo you could still buy Cuban cigars in Canada, and Air Canada made regular flights to Havana even when these flights were shut down to/from the U.S.
The Cuban embargo didn’t stop USSR, Poland and East German trade with Cuba.
Any country is within its rights to put sanctions on other country. To extent sanctions on trade by allies with a targeted country is an empire.
To extend sanctions on trade by non-aligned countries is piracy.