Not unstable at all. The NKs are only shouting loudly in order to get aid. If they are met with a tiny bit of respect and negotiation ends in "if you scrap your plans, you'll get rice and petrol" then it all cools down - until the next US/SK military drill.
But not unstable - Kim III has nothing. Even the rockets are empty plywood things covered with aluminium sheets. If you watch closely at the ones shown in parades, you will notice they are dissimilar from each other, have small bumps etc - and would not last many seconds if tried to be launched.