One reason Greenland is strategically important to the US is in fact twofold: 1. It’s the best place to set up anti-missile defenses to intercept ICBMs coming from Russia / China 2. It’s a very good place to set up offensive missile capabilities to threaten Russia / China The WSJ had a good graphic out a few days ago showing the trajectory of missiles from ICBM sites around Russia to the US would fly overhead or near Greenland, which also happens to be almost directly beneath where those missiles would reach their highest points (“apogee”) which is when they are most vulnerable to interception because they are traveling at their slowest speeds. If you throw a ball into the air you’ll see the same effect - the ball is slowest at its highest point.  And for an intelligently guided missile capable of trying to evade interception, you have an even better chance to shoot it down from a point directly beneath it since that is the closest path to the missile (i.e. least amount of warning time for the missile to realize an interceptor is coming). This above is all courtesy of our resident rocket scientist Phil. The US already has the right to dot Greenland with military installations, and I imagine that extends to intercepting ICBMs. Though Europe might object for some purposes.