Although in many scenarios nuke weapons for the most part will keep an adversary at bay. However small nations have few nukes and crude designs with rudimentary delivery systems, they can be taken out if the adversary has good intelligence. If they do use nukes against a force with superior nuclear fire power, its the end of them.
But thats the problem, isnt it? We have had 12 years to create an intelligence capability to find out what, where and how Saddam created WMDs. Yet here we are. We dont know where they are and what was done with them. What makes you think we have a better handle on the Korean weapons, or the Iranian weapons? Lets say you get the word that Saddam II is going to launch his crude nuke at you with his rudimentary delivery system (say, a Toyota pickup). Knowing what we know now quick where do we aim?
If they do use nukes against a force with superior nuclear fire power, its the end of them.
Fine. But in the meantime how many thousand of your troops are fried? And what do you mean, the end of them? Genocide?
Armchair strategists! ((sound of disgust))
Leaves us out then.