From the aforementioned interview.
"Taking out their nuclear potential would create a fallout," Russert pointed out.
Trump: "Tim, do you know that this country gave them nuclear reactors, free fuel for 10 years."
Did they. Bad America. Or...
The reality is that before 1989 North Korea was protected by the cold war. After.. well it was pretty busy in the 90s with the USSR falling apart, the Balkans etc, after that it was useful to have a low risk bogeyman to scare the public with, Canadian Bacon in the refrigerator.
The US has followed a doctrine of "perpetual conflict" since WWII as part of it's defense strategy, that is open and admitted. Keep finding ways to keep the troops sharp and the M.I. Complex well fed. Maintain a low level fever in the world to exploit for arms sales and bases etc etc.
Not dealing with North Korea was clearly intentional. Wag the dog. There is no risk from them any more than there has been for decades already. It is theater.
Let Kim JU feel personally safe, convince him he will not be a Saddam II and that is all required.
The game is not what the public thinks, the goal is to keep the US public thinking small.