while you can get into the semantics I think it was clear from 1945 to those in the know just how destructive they are. I think there's a unwritten policy that who ever uses them would face a retaliation both political and military on a awesome and unholy scale.
The thing is, they originally WEREN'T that destructive compared to the over all war. Way more were killed in the firebombing of Tokyo then in the nuking of Hiroshima, for example. They were just, once you developed them, cheaper and put fewer of your own men at risk. If the next war had started out or quickly grown to involve bombing cities to intentionally kill civilians, I think nukes would have been used with no second thoughts. It's a fluke of history that there was this gap where there was time for the idea of mass murder to become morally wrong.
(there's a great news clip in Atomic Cafe of future VP candidate Lloyd Bentsen calling for the use of nukes in Korea)
North Korea has only one card so it uses it whenever it feels cornered. There political system is at its end, [low production, mass starvation etc] so expect more on this front. but they know any serious war would be the end of there government.
within a decade north Korea will collapse. I'm taking bets.
A collapse would be horrible. There's every indication that the leadership is cut off enough to think lashing out in one final spasm would be better then just fading away, and even without nukes a suicidal attack on South Korea would be devastating. In a perfect world, whatever son takes over either slowly opens up the place, or he becomes the figurehead of a council of generals who know the military reality and they try to ease the country back from the abyss.
