Only they can't do it. Duh. More to the point if they do it today it is illegal, obummer made it LEGAL for them to have one. Try reading for comprehension.
What do you mean they can't do it? They can fire up those centrifuges any time they damn please unless our allies, Russia and China continue to vigorously enforce inspections. Obama made it legal

Obama did nothing of the sort. It is illegal per current international law but they don't give a crap that and neither does NoKo.
The agreement said nothing about them continuing to be bad actors in the region. It was about continued nuke development only. They were complying per the IAEA and our own intelligence.
Perhaps you could answer the question that nobody else can: Specifically what US interest was advanced by pulling out of the agreement?
They had ZERO chance of developing a nuke under the sanctions that were in place. Furthermore their economy was on the verge of collapse, then kerry and obummer came in and rescued them. By giving them all of that cash they then had the ability, with the removal of the sanctions, yet again thanks to obummer, to not only complete their nuke program, but also develop their ballistic missile systems, once again thanks to your hero obummer, to the point that when they get their nuke, they will then have a way of delivering it to distant targets.
With us reinstating the sanctions, they can't develop their nukes, their economy will suffer, and hopefully the oppressed people will finally get hungry enough to get rid of the scumbags. Yours is the philosophy of neville chamberlain. We KNOW how his ideas came out.