though I've been wondering whether he is following in the footsteps of dear old dad and dear old grandpa and saber rattling to get us to give them free stuff to go away

OR

has NK reached the point where all the years of yes men and killing off anyone who tells them things they don't want to hear has made them actually believe that they are a real threat to us. That's rather frightening because that would mean that he no longer has the threat of being slaughtered in his decision making and might actually do something.

The end result of that would be predictable and he and his entire band of idiots would be wiped off the planet, but the loss of life and cost to others (especially in SK and possibly Japan) could be extremely high.