In a declaration that redraws the map of Arctic influence, Donald Trump announced Thursday that the United States, Denmark, and Greenland have formalized a trilateral agreement placing American authority over Greenland's security affairs. The accord arrives at a moment when the far north has become a theater of great-power ambition, with climate change unlocking resources and routes that were once locked beneath ice. That three sovereign actors — each with distinct interests and histories — have arrived at this arrangement suggests the Arctic's strategic gravity is now strong enough to bend lo