Nuclear weapons speak words louder than th ear can bear. North Korea's supreme leader Kim Jong has been threatening for years to use such missiles on the U.S. and has even posted a video on what it would be like to drop one. Highly provocative and threatening behavior will likely be followed up by real violence in the future and the U.S. is right to act in this case.
In today's world there is no good reason to have such missiles unless one is reaching for power. They serve no appropriate function and no longer act as much as a deterrent. Nations who want to develop them in the modern world want to threaten others. The superpowers of the world made a mistake when allowing other countries to have these missiles and should clamp down quickly on any nation that seeks to develop or grow their arsenal now.
Despite their despicable nature the technology is no longer so advanced in the world of supercomputers that many closed and impoverished nations like North Korea will soon be able to develop them. The international community must come to serious coordinated agreement, not excluding complete economic collapse and sustained destruction of capabilities, for any nation that develops such weapons.
Kim Jong is under some type of delusional belief that he will make North Korea great while ignoring the economic principles that will take him there! His behavior is erratic and his threats are a serious sign of immaturity and a personality flaw. If he has the capability, there is a high likelihood he will use such weapons when he has a point to make, feels threatened, or his internal grip over the nation weakens.
China also has a responsibility to help deal with this situation and offer Kim Jong a final ditch effort to cease, desist, and dismantle its program. After this olive branch of opportunity to maintain Chinese relations is extended it is up to the civilized international community to act. Seek destruction of nuclear capabilities, if necessary regime change, and if absolutely necessary total serious economic hampering with substantial support for the already starving people of the country.