The problem with iran or NK having nukes is that the leaders of these countries are not accountable to anyone...nor do the rules of mutually assured destruction apply to these countries.
The leaders of Iran/NK can use the nukes with out having to answer for that use....they are not democracies.
Nor do the leaders necessarily care if their own people live or die in a retaliatory strike.
The bolded comment is very important. It is what made MAD a valid proposition for the since the dawn of the atomic age. There is the underlying assumption that the people of nuclear states don't want to die...nor do their leaders want to die. As bad as the leaders of the Soviet Union and PRC might have been at the height of the cold war, they had enough humanity, patriotism, or at least self preservation to see that their nations avert a nuclear exchange.
Can you say with absolute certainty that those conditions apply to NK or Iran? No you cannot. In fact it is quite the opposite.
1. NK-Kim has shown quite the disdain for the welfare of his own people for quite a long time now. I am sure he has some deep presidential bunker than none of our nukes can reach. If all his people die in the exchange, well so be it.
2. Iran-With the current "martyrdom" philosophy prevalent in the middle east, I don't think that these people are afraid of annhilation. Again, assured destruction is not an obstacle to them using nukes.
So, in either case, MAD will not work. It is incredibly unsafe and irresponsible to let these nations have nukes and the means to deliver them.
Besides...who really names a ICBM "Type-o-Dong"??? I mean REALLY!!
The Daily show had a really good bit on the various "Taepo dongs". Hilarious.