"The United States needs Greenland for the purpose of National Security. It is vital for the Golden Dome that we are building," President Donald Trump posted on Truth Social on Wednesday. Trump is right. Grab a globe and look down from the North Pole, or check out this official Pentagon map. You will see that Greenland is pivotal to the Arctic front. Greenland's eastern coast guards the Greenland-Iceland-United Kingdom or GIUK. This is the entry gate to the Atlantic for Russian President Vladimir Putin's nuclear-armed submarines. Greenland hosts important early warning radar sites because its field of view covers so much of the bomber and missile flight routes from Russia and China. No Greenland, no Golden Dome missile shield. That's why Trump lit a bonfire under Denmark and NATO to spur much-needed progress to counter aggressive moves by Russia and China.