In 2016, a crack in the ice opened beneath the site of the U.S. Navy’s flagship Arctic exercise several hundred miles north of Prudhoe Bay, Alaska, forcing experiments to end early and leaving researchers scrambling to evacuate. Five years later, an early freeze trapped roughly two dozen commercial vessels in the East Siberian Sea; some had to wait weeks for Russian icebreaker assistance. And during a Canadian-led multinational military exercise in 2025, allied forces encountered a difficult combination of conditions: extreme cold grounded helicopters, broke snowmobiles, and knocked out communications equipment even as thinning sea ice forced U.S. pilots to search 25,000 miles of coastline for a location thick enough to land on.

These were not failures by unprepared or inexperienced Arctic actors. They involved three of the region’s most proficient nations, each operating in territory it knew well. But there was a common thread: the Arctic has a way of humbling those who operate there. Its distances, darkness, extreme weather, and sparse infrastructure expose the limits of even the most capable governments and militaries.

This fact creates a paradox. The Arctic is a main approach to the U.S. homeland and a platform for projecting power at the top of the world. That is precisely why, as geopolitical competition intensifies, Washington is becoming increasingly focused on protecting sovereignty and securing its interests in the region. Yet no single country, not even the United States, can see, maneuver, and sustain itself across the Arctic. Effective sovereignty there relies on building networks of dependence.

This week’s agreement between Greenland, Denmark, and the United States illustrates the point. After months of negotiation, the three parties struck a symbiotic deal codifying U.S. military access while affirming Danish and Greenlandic self-governance. U.S. President Donald Trump has called it a win for American interests; Denmark and Greenland a win for sovereignty. Both are true, as nearly every mission that makes Greenland strategically valuable—missile warning, submarine detection, basing, and resupply—works because the United States is embedded in an alliance system.

The agreement could mark a turning point in how Washington approaches Arctic security. Trump’s early talk of acquiring Greenland or making Canada the 51st U.S. state cast self-reliance as the goal and strained relations with key Arctic partners. This agreement signals a more productive direction. Working with allies preserves the advantages the United States already holds and closes the gaps, in both presence and allied political unity, that adversaries are eager to exploit.

But fully embracing the role that allies and partners must play for the United States to achieve its goals in the Arctic will require a shift in a long-held mindset. For the United States, pursuing interdependence is an uncomfortable strategy. Self-reliance remains closely associated with national power, and Washington has historically approached Arctic shortfalls by asking what additional U.S. capabilities it needs to generate. Decades of deprioritizing the Arctic, however, coupled with the region’s vast and forbidding geography, leave the United States with little choice but to work closely with partners. In practice, the interdependence it needs to have with allies in the Arctic is already found everywhere—now Washington must continue to build on it.

The United States’ basic ability to understand and communicate what is happening in the vast Arctic region depends on partnerships. Arctic awareness remains uniquely........

© Foreign Affairs