Does North Korea have any right to possess nuclear weapons? The answer would have to be no. No State does have this right, to possess such weapons of mass destruction.
But this includes the West. The hypocrisy of the United States must always be stressed, that it is in no place to lecture anybody until it rids itself of it's own weapons.
Without making any apologies for the Kim regime - it is quite possible that it would not even exist (or at the very least not in it's current state) had it not been for the ferocity of the Korean war, which the US was contemplating making nuclear. That was in the day when Britain did not simply echo US foreign policy, when Clement Atlee was said to have had some influence within the 'special relationship' in persuading the administration not to do that (i.e nuke Korea). The United States is hated in South Korea more than anywhere else in South East Asia.
It is little wonder that the regime in the North is paranoid. It must be seen in the context of the history of the peninsula. The Soviets withdrew after the end of WWII, but the United States did not. Troops remained while a right wing puppet dictatorship that had almost no support among the population was installed and propped up. It was only relatively recently that South Korea became democratic.
The pro-Soviet regime in the North did initially have backing among the largely peasant based population in both regions (many in the South in fact welcomed the Northern troops as liberators). Councils did exist which represented some form of popular representation. It is impossible to say what the regime would look like had the country not been so devastated by war, or had the whole peninsula been under the regime in the North. But mere speculation leads one to suspect that it would look a little different than it does.
True, there is nothing defensible about the current regime in the North from any progressive standpoint. It would not be desirable for it to have nuclear weapons.
But as is Bin Laden and his friends in the Taliban, it is partly a product of US expansionism itself. What the US terms as 'rogue States' are not isolated products on the world stage. It is unlikely they exist in isolation from the world's only superpower either.
Update: Sanctions are now being considered following the nuclear test. These should be firmly opposed by progressives as they will only hurt the already hungry population of N.K