If the would-be invaders were "normal", they'd not go near populated areas. They'd just set up base wherever they wanted to extract resources or whatever. But

If the would-be invaders were "normal", they'd not go near populated areas. They'd just set up base wherever they wanted to extract resources or whatever. But the US already had excellent relations with Denmark and could probably have gotten mining rights or whatever they wanted without this weird display of power. The huge downside to that would be it would quickly demonstrate how incredibly expensive, slow and uncertain such mining operations would be. I must conclude the annexation of Greenland is mostly a play for the US domestic audience. Very similar to Russia - Ukraine. Maybe a way to put pressure on Canada too.