http://en.wikipedia.org/wiki/Nuclear_non_proliferation_treaty
The UN Nuclear Non-Proliferation Treaty has been on shaky ground since its inception. 189 powers signed into the treaty, but recently, North Korea violated the Treaty and is therefore no longer entitled to its benefits. It is legal for us to launch a retaliatory strike against them, if a nuclear or radiological weapon explodes on our soil (of any type).
China has nuclear supremacy: they have an estimated 14.7-1 parity against us. Most, curiously, are designed to malfunction: that is their enigmatic "nuclear strategy and security."
Like all significant disciplinary problems, North Korea has proven itself desperate, ill-funded, and irresponsible. Their recent launch of a strategic weapon delivery system DIRECTLY over Japan can hardly be misread: they intend to blackmail us any dirty way possible and seem to think that leftist sympathizers and spies in America will help them spread communism.
If that appears to be a little left of sanity, rest assured, it is.
Rest assured also that it is well under control. An angry little Chihuahua might snap at a well-trained Pit Bull, if the Chihuahua thinks the Rottweiller behind him will protect him.
What the yapping little Chihuahua forgot is that the Pit Bull is friends with the Rottweiller.
Our long association with China -- since the death of Chairman Mao and the end of the "cultural revolution," has done much to ease tensions.
If North Korea launches one of its antique missiles at us and a Perry or Ticonderoga class AEGIS frigate in the Pacific knocks it down, Korea just might find Chinese troops in Pongyang, converting that comunist hellhole into a robust, free-market capitalist nation with a better life for everyone.
When that happens, everyone can breathe a lot easier.