Their response would be rather passive not active. They would not go out and say their policy should stop. They all sing in chorus to vow the fight to the death until everything explodes around them and they have absolutely no means to fight back. I noticed a curious pattern of passive resistance in N. Korean's attitude toward their regime. It suggests that they want to be left alone. They are not active participants. Even elites vaguely feel that they are at the dead end, but somehow find no alternative to status quo.
I do not discount the fact that they were brainwashed, but they also know that they have no chance, and Kim Jong-un is not an endearing leader. He is less than what Hirohito was to Japanese during WWII. Their brainwashed mentality would cause problems after the shooting subsides and a new regime or occupation begins.
I think if war breaks out it will escalate so fast there will be little time for anything but preplanned reactions. Any general or subordinate not towing the party line would be instantly shot, blown to bits or eaten by starving dogs. One would hope NK itself would get rid of its aggressive leadership when faced with certain doom but I have trouble seeing how that would play out.
This is why I think talks with NK would be useful to communicate their dire situation. Probably would not do any good but heck why not try?