...a good place to start would be with these two recent entries from writers within the Washington Post family, both trying to explain what China is, is not, and might someday be doing about North Korea.
For analysis, you would turn to John Pomfret, who actually knows quite a bit about China (as shown most clearly in his book Chinese Lessons). In an entry last week on his Pomfret's China site, he explained how the nutty regime in North Korea looks from the Chinese perspective, and how much power the Chinese actually have -- and lack.
For speculation -- really, paranoid hysteria -- you would turn to his colleague Anne Applebaum, who has just asserted in Slate that China is encouraging the North Koreans to keep testing nuclear weapons and thereby create an international crisis. She says, after entertaining several explanatory hypotheses:
Personally, I favor another scenario, equally speculative: Perhaps the North Koreans have stepped up their war rhetoric and war preparations because China wants them to do so. I can't prove that this was the case--no one else can prove any of his theories about North Korea, in fact--but I can look at the evidence...
The "evidence" she lists will seem crude to the point of caricature to anyone with any familiarity with China. Even such familiarity as would come reading her colleague Pomfret's work. She ends with the flat-out statement:
North Korea is a puppet state, and the Chinese are the puppeteers. They could end this farce tomorrow. If they haven't done so yet, there must be a reason.
Many of the reasons -- other than deliberate Chinese war-mongering -- are precisely what Pomfret explains.