Austin Bay links to his StrategyPage note on how China has "lost face" with North Korea blasting off a nuke (or perhaps even a dud):
"In Shen's words, China's diplomacy has also "been a failure."

Kim's nuke test publicly exposes China's failure -- a major power's failure on its own border."

While I do not actually believe that China has lost as much face as Bush, and therefore has done relatively better (in losing less), Austin's conclusions seem correct:

"Forcing North Korea to kowtow (in the regional parlance) is a way for China to re-establish its political position.
But this must be done without resort to war. That suggests a land and maritime embargo of North Korea, with the Hermit Kingdom's borders hermetically sealed. An embargo is the "stick" the Bush administration's "six-nation" diplomacy lacked. Such a cooperative international operation might actually "pry the nukes" from Pyongyang. An effective embargo requires a committed China. It's time for China to demonstrate the political will to protect its own linked economic interests."

If Austin is correct about China's face loss, a tight blockade should be easy to arrange.  If I am correct, China will talk tough rhetoric, but continue supplying cover for Kim Song-Il's madness, and trade with the N. Koreans to keep Kim in power.

Joe Katzman at Winds Of Change discusses the N. Korea problem more clearly:
"Forget North Korea ...
The truth is that North Korea is an irrelevant bit player in this whole drama. The real player here is China. They have helped North Korea at every step, and North Korea's regime cannot survive at all without their ongoing food and fuel aid. Kim Jong-Il's nuclear plans may be slightly inconvenient to the Chinese - just not not inconvenient enough to derail a strategy that still promises net plusses to those pursuing it within China's dictatorship."

Joe claims China is pursuing a two-faced strategy, to avoid Kim's destruction (and having 25 mil. refugees on the border) while supporting anti-American forces in S. Korea.  The goal, Finlandization of S. Korea, with China having the veto power.  The answer?

"The biggest cost, and the only one that will be real to [China] in any sense, is to have Kim Jong-Il's nuclear detonation result in parallel nuclear proliferation among the nearby states China wishes to dominate/ bully. That would be a foreign policy disaster for the Chinese, and would cause the current architects of China's North Korea policy to be buried along with their policy."

Victor Davis Hanson is also calling for US support of democracies having nukes.  I think the idea of supporting other democracies having nukes is a great carrot for allowing more countries into the nuke club, but pushing democracy.

Yet I think a "democracy proliferation is acceptable" strategy is good.

However, for actually getting China to act, there should be an immediate 10% import tax on all Chinese goods into the US.  Until N. Korea disarms.  Or until China allows S. Korea/US/Japanese joint blockade inspections on trade going into North Korea, and only allow minimal food+medicine.
China pushing for regime change in N. Korea is the solution.
10% import tax, increasing 1% every quarter, is a better answer than proliferation.