[Grampa Dave]

How can a treaty/contract/agreement with a country, the USSR, that no longer exists be valid?

Only the Lunatic Left, their lawyers and the rabid anti Americans in the Senate like Osama Mamma Murray could even try to make the old 1972 Anti-Ballistic Missile Treaty still valid and in effect.

Are any treaties signed in the 1930's with Nazi Germany and the Imperial Japanese still valid when those Axis members are no longer in power?

[Poohbah]

How can a treaty/contract/agreement with a country, the USSR, that no longer exists be valid?

Quite easily. The US and Russia formally agreed in 1992 that all extant treaties remained in force until their scheduled end dates (if any).

Additionally, by your logic, we would have had to surrender Alaska to the USSR in 1917, as the collapse of the Czarist regime would have invalidated the treaty by which we acquired that territory.

[Ernest_at_the_Beach]

Are any treaties signed in the 1930's with Nazi Germany and the Imperial Japanese still valid when those Axis members are no longer in power?

If a new company moves into the old building you don't have a contract with them!

[Excuse_My_Bellicosity]

No joke, the USSR isn't even a real country anymore. Is a treaty with the African country of Rhodesia still in force? Of course not, the country is now Zimbabwe and is under a totally different government!