I tend to think that the nukes designed and made by the Putin regime do work because we know (because the Soviets successfully test 100s of nukes) that the ones designed and made by the Soviets worked, and no one is claiming that the Putin regime is much more corrupt than the Soviet regime was.

(Since the fall of the Soviet Union, the Russian arsenal has been replaced: the only parts that survive from Soviet times, I think, is the fissionable material.)