even if we'd let the Communists keep the South in 1950, the PRK might still be a problem. It would still have an adversary in Japan, and Russia and China would still be switching off the "uneasy partner" and "unfriendly neighbor" role....Although Jim is talking only about North Korea, in fact the conditions he specifies are widely applicable. The "problem" state is (a) destitute, (b) bordered by another state that is worth deterring, and (c) tempted to try extortion. How many countries does this apply to?
The PRK would still have an incentive to pursue nuclear weapons. And socialism would still suck. So the PRK would likely still become a nuclear-powered basket case, or anyway try. And it would still be tempted to extort benefices from rich countries or make money selling its weapons on the black market.
Now (a) is surely a result of (sustained) socialism. So we have to limit this to very socialist states. Deterrence applies to practically every state; they all have armies for this reason. So that does not remove anyone except maybe Costa Rica. And (c), temptation to extort, would seem to be applicable to just about everyone too, at least in theory. All it really boils down to is that people are greedy, and that certainly applies to statesmen.
Even if we chalk up (c) to despotism, we are still left with a rather broad set of states which would seem to fit the bill. Many African nations, for example, are despotisms. That they don't have nukes is a function of complete lack of infrastructure and technical ability. Perhaps they will in the future. And then they will be just as well placed to strongarm the USA as North Korea is now.
But before we become neocons and want to invade the world, two things are worth thinking on. First: that at least two nations have already been socialist, despotic, and poor: the USSR and China. They certainly did pursue nukes, and they got them. Both countries have been problems for us, but neither has sold nukes to terrorists. It seems that while they were poor, they were not destitute enough for that, which, if you think on it, makes sense. Providing nukes to terrorists is a dangerous way to make money.
Why, in spite of their socialism/despotism, did the USSR and PRC not get desperate enough to sell nukes on the black market? It seems that in both cases, when the economy failed long enough, they reformed. North Korea has not reformed, thus far. Will it? Is the current situation transitory? I think so.
So much for the supply side of the problem. On the demand side is a standard libertarian argument for a noninterventionist foreign policy. Terrorists want to attack us because they believe we help oppress them, which is, at least in part, true. We can stop oppressing them. If "they" don't want to hit back at us, then the existence of a few black-market nukes is tolerable.
Of course, meanwhile there is a problem. We are, currently, interventionist, so any terrorist nukes are a problem. Isolation is one way out; I don't see any other. We cannot rule the entire world (or even "just" Africa and the Middle East) at gunpoint. (We can't even rule just Iraq!) Nuclear technology will continue to get cheaper, as technology in general progresses. North Korea may be only the first in a line of nuclear despotisms that we have to, somehow, deal with. I suggest it is time for us to repent: time to pull back to Santa Monica. Now, while we still have a few years to repair our image in the world.