Tell that to the families of everyone who's died in the Russian war on Ukraine.
You know that Ukraine had nuclear weapons, and gave them up for the promise of never being attacked?
Would Russia have spent the last 11 years attacking Ukraine if it were still a nuclear power?
(Maybe. Dictators are not reknowned for their sanity and good decision-making skills.)
It wouldn't change anything, Ukraine doesn't have the infrastructure to maintain those bombs.