Seemingly threatening acts calculated to trigger a response..
Then Kim can claim "innocence" in his actions, as there was no real threat...
Kim can also claim victim status with possibly the U.S. as the bullying aggressor..
Public relations and International politics may then be leveraged in N. Korea's favor..
Possibly such a leverage could be used in future six-party talks..
Just a wild guess, but it sort of fits with past behaviours..
They only have one main script, which they use again and again.:)