> The US hasn't withdrawn from CUSMA. On July 1st it declined to extend the agreement past 2036, which isn't the same thing. The deal stays in force until 2036 with annual reviews, and no withdrawal notice has been given.

> Also, the 6 year review is about whether to extend the term. Withdrawal is a separate clause that a nation can use at any time on six months' notice.

These are good corrections; I was merely oversimplifying. The main point is that what Trump is doing is not some kind of horrible betrayal, he is simply using the terms of the treaty as written. The treaty explicitly specifies how and when either party can renegotiate, decline to renew, and withdraw. You could argue that the treaty ought to have been more permanent than that, but then your beef is not with Trump but with the Canadians who agreed to the treaty as written.