Thankfully, we have a lot of experience with disarmament deals with nutball regimes. Let's review.
The WMD deal with Iraq was violated by Saddam who secretly kept WMD programs for a while, then refused to verify he no longer had active programs, and kept the ability to reconstitute the programs despite inspections.
We went to war with Iraq.
The nuclear deal with North Korea was violated by the Kim dynasty and now North Korea has nuclear explosive devices (if not deliverable nuclear weapons yet).
North Korea repeatedly threatens us and our allies with destruction. And their regime make even regular nutballs look better by comparison.
The WMD deal with Libya still left a psychopathic dictator in charge of a mostly de-WMD's state.
We went to war with Libya.
The nuclear disarmament deal with Ukraine worked. But sadly Ukraine probably regrets that decision given that they've lost significant chunks of their territory to Putin.
The chemical weapons deal with Syria left a psychopathic dictator in power who still used chemical weapons inconveniently left off of the deal.
The death toll mounts in Syria, jihadis run wild (and crossed into Iraq to take Mosul and the region), and our involvement against most sides in the civil war ratchets up.
And now we have a nuclear deal up for approval with Iran.
But this deal will work much better, we are reassured.
But hey! We'll always have Khazakstan! Whether they'll retain that secure feeling as Putin casts longing glances their way, we'll see.
And no, I don't count South Africa. For whatever reason they gave up their nukes, nobody had to make them do it.