Greenland is only a military concern for the US, if the US abandons the NATO "musketeer oath" and abandons one of its most steadfast allies, Denmark. I'm not arguing that would not happen (because... Reality), I'm simply saying that this argument is self inflicted and thus very pointless.
The US already has an air force base on Greenland and enjoys essentially freedom of movement there. This freedom was planned to be expanded to the rest of Denmark, but I'm doubtful that will pass parliament now. There's obviously no public support to be found for this currently.
If the US simply adheres to the known world order, noone would touch Greenland. Wonderful as it is, it simply isn't worth the very difficult and sustained conflict that would follow.
This is nonsense. Greenland is, and has been, "open for business". 28 individual entities have been awarded licenses to search for and extract raw materials in Greenland. Of those, only one is a US entity.
If the US had any interest, one would assume applications would exist and it would not require/excuse an invasion.
Same for real estate development.
Invade it, to be blunt.
If you zoom out and consider Panama and Gaza also, I believe the sole reason at play here is Trumps desire for his legacy to be the first president in "almost a century " as he would likely phrase it, to add territory to the United States.
I believe Canada was briefly at play/mentioned before the inauguration too. But I'm sure even Trump understands that picking a fight with someone landlocked with the US carries the inherent risks that are very difficult to explain or justify.