The North Korean elites might willingly sacrifice half of their population in a war of their choosing, since almost half of population of North Korea is in the military.
Videos of their military parades show a hoard of malnourished, brainwashed, young (and old) conscripts.
This chart, which shows military strenght comparisons to the US and other nations is troubling.
http://en.wikipedia.org/wiki/List_of_countries_by_number_of_troops
If the idiots that are feeding NK would cut off the food supply then NK would shrink in size. Attrition is effective.