He's not going to give up his nukes. He's seen what happened to Saddam and Gaddafi when they gave up their WMDs.
We may debate whether intervention in Libya was justified or not, but it essentially wrecked all future efforts to convince various regimes to disarm.
I'm not a fan of nuclear weapons spreading everywhere, but I'm surprised at people who can't understand why countries are unwilling to give up their nuclear capabilities. It's not just about various unpleasant regimes. Ukraine had voluntarily gave up its nuclear weapons in exchange for the Budapest Memorandum which proved absolutely useless. When "nuclear disarmament" is concerned, there's a great deal of hypocrisy. We have five "recognized" nuclear powers essentially enforcing their unfair advantage over the rest of the world by denying the nukes to everybody else. It's not about peace or stability, it's just about five or seven powers cementing their superiority.