The North Korean leader feels he must prove something all the time to show that he is a tough guy, The USA has the right to protect its ally South Korea, But this show of force by the Americans will escalate into something else entirely, I wish they have diplomatic talks rather than a show if aggression.
I don't think that the situation will escalate further. For sure Kim Jong Un is a maniac. But he knows his limit, and all he want now is a good bargain. The removal of THAAD from South Korea will be enough to satisfy the North Korean dictator.