Pblakeney
Guru
Many commentators saying it's an ego issue for Trump. He wants to be the President that added the largest land area to the US.
(Everybody here and everywhere pointed out that they already have treaties allowing them pretty much everything from a military/security perspective, that Denmark/Greenland are already talking to mining companies about mineral extraction, etc.)
That's as maybe but he has also said that he wants Canada too.
Look at the map. If he takes Greenland then Canada is surrounded* for all practical purposes. Taking Greenland first is a good military tactic.
*Cut off supplies via Hudson Bay, the St. Lawrence and Halifax etc in the east plus between Alaska and Oregon in the west.