You can deride Trump all you want with your infantile comments, but the fact is that NK  is ruled by a man who considers himself a God. Kim Jong-un is insane as well as most of his close Generals. 

He just had his own uncle executed along with dozens of others close to him.

NK is an estimated five years from having a working ICBM that could reach North America. It would probably be shot down.  But what if it was released from a ship at sea or a submarine?

The time for action is now when it is still possible to eliminate him.  Not in the near future when removing him might be an impossibility.