Ignore the Nukes completely. Accept that they've got them and that is the "new normal". There is nothing you can realistically do about the human rights abuses either without blowing the whole place up like Iraq. The population are not likely to welcome an American occupation after fifty years of brainwashing. You have no control over a regime that willing to starve its own people to protect its independence. So go to the root of the problem.
Invite Kim Jong Un to the US. Let them have their propaganda "victory" and they can claim they subdued the American Imperialists. They can feed that back to their own people in the news reels. Give North Korea Diplomatic Recognition from the United States (its never had it) and set up an embassy. We're only talking pride here. pride is cheap.
Send the President of the United States to Pyongyang for a series of talks to prepare the ground for a formal peace treaty that ends the Korean War with North Korea renouncing all claim to South Korean territory. Throw in a generous aid package to develop North Korea's
Oil reserves so they can become energy independent to make sure they reach an agreement. Lean on China and get them to offer some additional economic assistance as their "ally", particularly with food and agriculture. Open up the border with South Korea and let them get their hands on new consumer technology.
Pretty much
every outcome of that in the short-run is good from the US point of view. You break the ice, start diplomatic relations and get peace talks moving. They still have nukes for deterrent purposes
but you've just taken away any reason for them to use them offensively within international law. The
long term problem is whether this backfires and makes them stronger, but that's North Korea's decision.
North Korea is not looking for a global empire like the Nazis, they want unification of "their" own people. The risk of appeasement is comparatively smaller because they only want South Korea. If you say to them "this has been going on for 50 years- do you really want to risk a war for this?" you at least are going to get a pretty straight answer and clear the air. The West doesn't want a war, neither does China and so give North Korea the option just to walk away. If it accepts a peace treaty, it just gave up its primary objective. it can let history be history.
You can't stop them if they really want a war but you given them a really good reason to take the Chinese model of liberalising their economy. At a minimum you will have helped the north korean people
slightly by creating conditions to improve their living standards. Whether their is ever a "free" Korea in the North is out of your hands. If they
still decide to go to war in a decade or so time, they will be strongly militarily, but diplomatically it will be so obviously an act of aggression there is a pretty good chance that not even Russia or China will want to help them. It at least buys time and kicks the issue down the road. You at least giving a long-term solution a chance.
After all, Republicans are good at this sort of thing.
