Kim Jong Un is playing a defensive game, using his offense to create his defense. It is like in hockey, during the last 30 seconds, when a team will pull the goal tender so they can apply so much offensive pressure, allowing the defense not to be needed. North Korea is stable, as long as there is little outside influence to change anything. It is similar to an abused wife, in a marriage, who is isolated from her family and friends. She can be made to accept her less than optimized circumstances, through a type of Stockholm syndrome, where she begins to relate to her abusive captor and starts to justify his behavior. If her friends and family was to enter the picture, this could destabilize that less than optimized situation. He need to scare them away using offense to mount a defense. Kim Jong Un uses the military and his quest for nukes to keep everyone away, so Stockholm syndrome stability is maintained. He pull the goal tender and mounts the perception of offense to create a strong defense against any change. As an analogous example and solution, is the Democrats pushed the Russian connection issue, hard in an attempt to discredit Trump. They never had any proof, but only the constant threat of uncovering a bomb shell. This offensive measure was actually a defense. When Trump accused the Democrats of wire tapping, they backed off, since this was what they were trying to defend against, by attacking and blaming him for this. Trump figured out how to make them blink. But he did not take them out like many would have wanted. It is likely he will make a similar offer to N Korea, that will make the feel less defensive and therefore less offensive.