Good question, but I'm pretty sure no one knows the true answer. The military probably does have an idea of their relative strength compared to the US/ROK, that might cool things down. As long as every provocation is meet with the "West" backing down, we risk the time we don't and the power in NK decides their bluff has been called. Do they fight to save their face or lose face. The Koreans, in general, are a strong bastion of "face".
GF