There are reports that Trump scared the hell out of South Korea and Moon made up the whole thing to stop the war. Even a shooting war risks the possibility of spillover into Seoul. The US can't be trusted with agreements in any event. Besides the recent cited cases of Iraq, Libya, and Syria, there is bound to be another change in the US government where an incoming president will try to find a way to circumvent existing agreements.
Head of the most powerful country, casually murmuring that he can push the big red button, which will kill millions of your country men, who wouldn't be scared to death? And now, John Bolton, the failed neocon with Iraq, creating ISIS and Libya, having Trump's ear and about to repeat the same thing with NKorea. Who will trust Washinton? Trump is different in temperament but not in policies. If a shooting war happens that will spread into Seoul in no time, then SKorea better be ready to remove all US bases, prepare for new world order, and not be afraid to align itself with China, and against Japan/USA, which will be a similar frontline along the Europe/Russia. That will bring respect from Washington, and all will be fine.
When millions of your people are at risk of being killed, anything is possible and I would seriously consider a complete realignment relative to former allies and enemies.