I think they'd be better off if we traded Puerto Rico for Greenland. We get the security of having territory in the Arctic, and the Danes get a Caribbean vacation resort island to get away from all the Scandanavian cold winters.
President Trump can even throw in constructing a luxury hotel and world-class golf club to sweeten the deal.
It's a win-win for everybody!
-PJ
The Danes should have contracted the Americans in the '50s and started to extract natural resources. At the same time, build a naval base there.
But they didn't do that so they don't really own it.
One day, the Chinese or the Russians can just show up to Greenland and they'll take it.