Mr. Trump is undermining these interests with his push to take control of Greenland, a semiautonomous territory of Denmark, despite vociferous resistance from Denmark and Greenlanders themselves. He is attacking the shared values to which democracies have aspired for decades: the rule of law, recognition of national sovereignty and respect for self-determination. Mr. Trump is causing what Prime Minister Mark Carney of Canada this week called “a rupture, not a transition” in the world order.