[Huck]

Regarding the dissolution of the USSR, I found this blurb from BBC News:

Following the 1991 dissolution of the Soviet Union, Belarus, Kazakhstan, Russia and Ukraine ratified the treaty and took on its obligations.

The Heritage Foundation chimes in here:

THE ABM TREATY WITH RUSSIA: THE TREATY THAT NEVER WAS

A much better argument, and interesting to read, but not related to the question of how treaties may be terminated under the Constitution. I believe, based on my reading of the arguments, that Congress should do it.

[general_re]

I'm with you - I've never found the Article II/Curtiss-Wright argument to be particularly persuasive. It seems clear to me that if the making of a treaty requires Senate approval, then Senate repeal ought to be a component of withdrawing from treaties. The executive does not have the power to unilaterally withdraw the US from treaties, IMO.