So like here is a totally crazy idea. NK has been isolated for over 50 years and it simply hasn't worked, they are kept outside in the rain and threatened, and then we wonder why they play the big tough back. So the crazy bit, how about instead of escalating things we actually try and convince them to come and join everyone else at the party.
If India and Pakistan can get by without nuking each other, then really I think that NK can do it. If we stop treating them like the outcasts and enemy, maybe they'll stop acting like it. So my suggestion is that instead of threatening them, we sell them stuff, get rid of the embargos and start trading with them. The thing is that it's very rare for countries to attack trading partners because they are generally better off being able to trade with those countries rather then fighting them.
Look at China and the US, ideologically they are opposed, but they are unlikely to go to war as long as they need each other tradewise. Start trading with NK, and it takes the whole sting out of what they do, they can't play the same cards, but rather would find themselves drawn into the way of the world with the rest of the nations on Earth and it's do the same to them as is happening to Iran and Cuba.
Trade and the ability to gain wealth will override the desires to go to war.