north korea is not more of an issue because even though it has a few nukes it is less likely to actually use them. china and russia have historically supported the dprk. the u.s. and japan have supported the rok. truth be told, nobody in this group wants to go to war.
china especially wants to keep the peace for economic reason if nothing else as the u.s and the dprk are china's number 2 and number 1 trading partners respectively. i think that the number 1 problem with the dprk is an exagerated sense of pride that would make them do something stupid just to prove they could.
this (overly condensed and simplfied post) is partly why we want china and russia involved in taming kim jong il. they were instumental in creating and supporting the dprk. both kim jong il and kim il song(sp?) looked to them for support and advice. if china is telling them to do something it is more likely kim jong il will do it then if we are telling him to do something. currently we can be fairly confident that china doesn't want to go to war with us. so long as we can agree not to try to kill each other it is safe to let china pressure the dprk to do what we want.

just my simplified and condensed opinion

oh yeah, for a good book try "the two koreas." very informative

00 black/tan svt, #2052 of 2150, born 2/1/00 formerly known as my csvt "Nothing in the world is more dangerous than a sincere ignorance and conscientious stupidity." -Martin Luther King, Jr.