I could be wrong, but I think the US agreement with Denmark gives the US the ability to just build a new base if it wants to. He could have just done it.

I think there are 2 reasons why he didn't go this route:

Bringing in a new state would be a big political win for him.
Greenland is rich in mineral deposits that the US can't have without making Greenland part of its territory.

[–] adb@lemmy.ml 2 points 12 hours ago* (last edited 12 hours ago)

Personally, I choose to believe he was just zoning out one day during a meeting with a big Mercator-projected map on display and he was like “wtf is this bigass piece of land right next door? Whatcha mean this isn’t an actual country? Let’s claim it then!” Then his yes-men counselors all came up with actual strategic reasons for this (minerals, halfway between the US and Russia, etc…)