“Important for all nations to know that US agreements have an undisclosed expiry date.”
Like the U.S. Constitution.
It is ridiculous to claim that a verbal promise made by a Secretary of State, never disclosed, never reduced to writing, and never ratified by the Senate would bind future Administrations. If that were the case, then Obama, Biden, or whomever could make any promises they wanted to other countries, never submit them to Congress, and subsequent President would be required to follow through.
The Constitution itself rejects that.
Nobody believes that, and neither us nor the Soviets believed Baker was binding the U.S. forever. The only reason people are making such a ridiculous argument now is because of their fetish for Vladimir Putin.