Put a narcissistic personality disorder (Trump) at odds with a anti-social personality disorder (Kim) and neither is going to back off. Expect missiles to fly people! Now normally the U.S. congress would and could stop this. Why do you ask? Because a declaration of war is a unilateral treaty according to the U.S. constitution, meaning Trump can't declare war, he needs congress for that. However North Korea is a different situation according to that same constitution. If you recall a history lesson about the fifties you would know the Korea war officially never ended, only a ceasefire was declared.