Military actions raised a whole new set of concerns for Beijing. DIA analysis divided military contingencies into two main categories: war as the result of North Korean attack, and war resulting from a U.S./U.N. attack on the North. If Pyongyang attacked South Korea, China would likely avoid giving military support and would work to end hostilities. But, if U.S. and South Korean forces pushed into North Korea, it would face a dilemma. In a worst-case scenario, the report suggests that Beijing might deploy Chinese forces across the Yalu River to prevent the whole country from being overrun by the Americans and their allies.

Whether that would still be the case today is an open question, but China’s perspective does seem to have changed recently. Whereas it refused to back U.N. sanctions two decades ago, last month it supported (and in fact helped the United States draft) new U.N. sanctions in response to North Korea’s recent nuclear test. That suggests it sees an increased need to rein in the North Korean regime and has a decreased tolerance for destabilizing actions. In public, Beijing has stressed that it will not accept “troublemaking on China’s doorstep.” While it is not likely that China will abandon its North Korean ally given its fear of unknown consequences, its analysts may well be scratching their heads (as their American counterparts are), asking what Kim Jong Un’s endgame is — or whether he even has one. And, if a war breaks out, will prior consultations between Washington and Beijing reassure the Chinese that our own endgame does not threaten their core interests or require military action to keep trouble away from their doorstep?