From The Times: As international tensions over North Korea have soared, China has deployed extra combat units of the Peopleâs Liberation Army (PLA) to man the border from the Yalu River in the south to the Tumen River near Russia - evidently fearing the risk of chaos and collapse. ... Beijingâs main fear is that if Kim tests a bomb - the CIA believes he has enough plutonium for four; other US experts think more - then Japan will feel it has no choice but to acquire its own atomic arsenal. That would destroy the balance of power in northeast Asia that has kept the peace since the end of the second world war. Chinaâs secondary fear is that if Kimâs regime collapses, hundreds of thousands of desperate, hungry North Koreans, some armed, will flood across its border to sow unrest and instability. "China on alert over a nuclear neighbour" by Michael Sheridan. 8 October 2006 http://www.timesonline.co.uk/article/0,,2089-2393599_1,00.html Apparently desperate North Koreans have already been seeking refuge across the Chinese border. The linked article is notable for an infuriating description of what they face when they are caught and handed over to the North Korean military.