Ah, good point, but that article also mentions (towards the end) that they are likely to just ignore the treaty, as Uruguay has (and some US states). They can also demonstrate that they are legalizing as a more efficient way to control/limit drug use.

As a Uruguayan I can tell you that unfortunately, ignoring treatises has had consequences - the U.S. banking system has issued some dire threats for us.

American banks, including Bank of America, said that they would stop doing business with banks in Uruguay that provide services to anything marijuana-connected.

https://www.nytimes.com/2017/08/25/world/americas/uruguay-ma...

Likely, yes and I think that is probably the right course of action, but IANAL, at least politically.

As I understand the US situation the federal level, the signatory of the treaty, didn't actually legalize anything. The states did, in breach of the federal law, but they are not signatories of the treaty.