If North Korea declared that it will no longer obey terms of the truce, then technically, we are still at war.
A President with a spine would bomb the sh!t out of them right now!
I know I would.
With an adult as POTUS it would be extra special if the US turned an air base in Iraq over to the Israeli's for about 48 hours while the USAF took care of NK. Two members of the axis of evil taken care of in a couple of days. What would the rest of the world do? Nothing.