For two centuries now, the so-called “Great Game of Nations” has been centered on the shifting boundaries of Central Asia and its surrounding regions, with Great Britain and Russia, later joined by the United States, China and Turkey, vying for power.

Suddenly, In an historical blink of an eye, that focus has changed. Today, supercharged by the ambitions of President Trump, it’s the Arctic. And the lineups of friends and enemies have been scrambled beyond recognition.

For most of modern history, the Arctic was not a battlefield. It was a barrier—a frozen lid on the top of the planet that separated continents and contained the shortest, most dangerous flight paths of the Cold War.

During that era, the Arctic’s strategic meaning was almost entirely military and almost entirely vertical. American and Soviet bombers, and later ballistic missiles, could cross the pole on the shortest route between civilizations. The Arctic was not a marketplace. It was a warning system. Radar lines, under-ice submarine patrol routes and remote U.S. air bases like Thule (now Pituffik Space Base) in Greenland existed for one reason: to detect and survive the opening minutes of a nuclear war.

That world is over.

Today, the Arctic is not a lid. It is becoming an ocean.