>The US is a superpower, but that doesn't mean that other nation-states exist because we deign to suffer their existence—that's a very colonialist way of looking at the world.
This is a question of international consensus, not US will. Under the definition of sovereignty agreed upon by the international community, DPRK has forfeited its' right to sovereignty by repeated human rights abuses, WMD development, and aggression toward it's neighbors. Essentially, if a state fails to uphold it's responsibility to its' citizens, sovereignty is forfeited. Admittedly this is a hard thing to judge, but a line must be drawn somewhere.