If they made the call proactively they could hardly be certain we would back them; Israel could tell them a few stories about that, and they are on the LONG end of the nuclear stick (at least until North Korea fulfills Irans nuclear arms ambitions, which is another factor here.) On the other hand, the leaders calculating those odds are directly in front of the one of the largest artillery concentrations in history, and atomic artillery shells are disturbingly easy for an atomic power to produce. If they wait for North Korea to make the decision easy, they may not like its consequences. It must be an incredibly terrifying helpless feeling, because whatever they do they are ultimately subordinate to what North Korea, the US and China decide.

Sadly, the best case, at least in the short term, may be to hope this is just the latest episode in North Koreas long history of extorting the food and fuel they desperately need but do not PRODUCE because they spend all their limited resources on weapons. It is a little pathetic: America has fought the longest war in our history for >60 years against a tiny impoverished bomb crater—and seems to be LOSING.