Well the first thing I would do would be to stop holding war games off the Korean coast.  What possible good can come from them?  Does anyone really believe Kim is going to disarm because of them?  Then I would bring in China and Russia etc and work on hammering out a real peace treaty.  Calling him names like Rocket man is not going to do much.  Hard work will be required, something the Donald knows little of.  

If war results many will die regardless of who starts it. It is far better not to start one.