Re: The US would have destroyed them years ago for unrelated reasons if they had oil.
Humour me for a moment, because I'm not suggesting it ever could be the case, let alone would be, but just for the purpose of making a related point:
Just suppose North Korea were a successful nation - financially and socially. Imagine some time in the future when the current regime is gone and some local equivalent of Pirate Party mentality infiltrates and takes over The People's Party. A humane, socially liberal collectivist government of the people, by the people and for the people takes over and makes a success of things.
Maybe people aren't obscenely wealthy. Maybe there isn't a 1% sitting around on yachts made of solid gold, pooping into toilets cut from a single diamond each that everyone can aspire to. But people have a decent standard of living. Let's say it's a bit like one of the Scandinavian countries - horrendous taxes but people get paid enough to be able to afford them and the trade-off benefits are considered worth it. It's not some Marxist/Communist utopia but there have been, and still are, worse places to live.
Well, the problem with that would be that our own 1% couldn't threaten rest of us with the horrors of collectivism any more, could they? Because people would point to North Korea and say "Well, it works there! It's better than what I've got here anyway."
So, whether they have oil or not is immaterial because, no matter how miserable life there might be, what we can't have is people agitating for an alternative social contract that means our 1% would have to stop being as obscenely wealthy as they are.
So, you nip it in the bud, don't you?
It doesn't matter how unlikely it is that the North Koreans might ever attain the dizzying heights of 'down and out in Scunthorpe', you make sure they don't even start looking like they might ever get that far - or people here will start asking awkward questions about why they can't, themselves, aspire to 'a bedsit Bognor' instead of the 'share of a campbed in a flea-ridden hostel in Eastbourne' they have to put up with today.
My point is that it's not always about anything directly tangible - sometimes it's about political pork futures.