Do not tell me. What Koreans can do against the Americans? Old Soviet weapons? Americans do not need a North Korea. They will not fight in the woods. They will destroy the entire military infrastructure, and Kim. Then the Koreans themselves are happy to join with South Korea.
Remember the resistance faced by the Americans in Vietnam? To get an idea about how tough the DPRK will be, imagine that the invading forces will face ten times as much resistance as they faced in Vietnam four decades back.
Why do you think that the Americans will carry out a ground operation? I think the Americans will just destroy the rockets and bombs the entire infrastructure of North Korea and the special forces will destroy Kim Jong UN. This will be enough.