If Japan had of had them during ww2 they would have used them. If Germany had them they would have used them. So if they get them they just might be stupid enough to use them. Just think what would have happened to that backwards country if that meteor that hit Russia had hit them instead. They would have thought they were under attack and fired one off.
They'll cause a nuclear war and destroy the Earth. Plus, we would know and we would try to shoot it down while it's over the Atlantic, like in COD4. But if they send all of them(I don't know how many they have, like a lot), then everyone will die.
I'd like to say that the answer is just no, but nowadays you never know what people are capable of. The US has been somewhat protected against nuclear war because of our second strike capabilities. North Korea would have to get close to our borders to even put a plan into action and with technology as advance as ours the possibility is just highly unlikely. and trust me, they are be watched like no other. Always have been.