What Does the Greenland Deal Mean for North American Security?

In the early months of 2026, Greenland appeared to be at the nexus of an existential crisis within NATO. President Trump’s demands to annex the territory, and refusal to rule out the use of force to accomplish such an objective, triggered shock and unanimous condemnation from other alliance members, leading the president to back down. Then, on September 22, on the margins of the United Nations General Assembly meeting in New York, the United States, the Kingdom of Denmark, and the Government of Greenland signed an agreement to update the 1951 defense agreement between Washington and Copenhagen. The agreement holds significance for Greenland, Denmark, the United States, and the other North American Arctic nation, Canada.

Q1: What’s new about the agreement?

A1: For the most part, the agreement is less groundbreaking than headlines suggest. The new deal amends and supplements the 1951 Defense of Greenland Agreement, which already grants the United States sweeping military rights on the island. Under the 1951 agreement, Washington may establish and operate “defense areas” in line with NATO plans, station forces and equipment there, and move freely between them by land, air, and sea, including through Greenland’s territorial waters. During the Cold War, these rights underpinned a U.S. footprint of 17 military installations and more than 10,000 personnel. The 2004 Igaliku Agreement consolidated the U.S. presence at Thule Air Base in northwestern Greenland, now Pituffik Space Base, and gave Greenland a formal voice in the arrangement, but left the core access rights intact, including the procedure for establishing new defense areas.

Against that backdrop, three elements of the new agreement stand out:

1. The agreement strengthens certain access rights and enables the United States to expand its military footprint immediately. It allows the United States to establish two additional defense areas at Narsarsuaq, formerly the site of a Cold War–era air base in southern Greenland, and Mestersvig, currently a military outpost on the island’s east coast used by a Danish special forces unit, while also authorizing the United States to modernize and expand its activities at Pituffik. The preamble also mentions establishing a Golden Dome missile defense system. Moreover, the deal strengthens the 1951 agreement’s provisions for free movement between defense areas by land, air, and sea by explicitly granting unrestricted undersea access within Greenlandic territorial waters.
2. The new agreement is permanent. The 1951 agreement is tied to the duration of the North Atlantic Treaty, while the new agreement has no end date, can be amended only by mutual consent, and binds a future independent Greenland to remain in NATO and assume the Kingdom of Denmark’s obligations under the deal.
3. The agreement limits future foreign investment by other states. Washington will have a formal say over whether entities from non-NATO, non–NATO partner, and non-EU states can invest in critical infrastructure and strategic sectors in Greenland, including in the extraction of natural resources. The agreement also bars non-NATO states from establishing military installations on the island without the consent of all three parties.

On paper, these are substantive changes. In practice, however, the new agreement mostly codifies what Washington could already do. Expanded access, basing, and overflight rights were already available under the existing framework—Washington reduced its military presence in Greenland after the Cold War by choice, not because Copenhagen or Nuuk stood in the way. The foreign investment provisions are noteworthy as China and Russia continue to eye emerging Arctic shipping routes and critical mineral deposits, even if, despite President Trump’s repeated claims, Chinese and Russian military activity in the waters around Greenland has been negligible. But the provisions hardly constitute a groundbreaking change to the status quo. The Kingdom of Denmark is a staunch U.S. ally with no appetite for Chinese or Russian strategic footholds on its territory. Copenhagen blocked a Chinese firm’s bid for the abandoned Grønnedal naval base in 2016, and U.S. diplomatic pressure and coordination with Copenhagen led Chinese bids to build Greenland’s new airports to be dismissed in 2018.

Q2: What does this mean for NATO?

A2: The crisis triggered by President Trump in early 2026 was unprecedented as NATO appeared to confront the possibility of military action by the alliance’s most powerful member against the territory of another member. During the height of the crisis, the Danish government reportedly prepared contingency plans to destroy airports and other critical infrastructure in the event of a U.S. invasion. The conclusion of an agreement between the United States and Denmark hopefully allays these fears and provides a pathway to return to a more constructive dialogue around Greenlandic security and defense. The naval domain is a particularly fruitful area for increased NATO engagement, as Greenland, together with Canada and Iceland, controls key approaches from the Arctic to the north Atlantic. Meanwhile, greater cooperation on critical mineral projects will take time, but could still be a boon to both U.S. and allied defense industrial initiatives.

Still, points of friction persist. The new deal’s duration is not tied to the continued existence of NATO— unlike the 1951 agreement—which could be construed as an attempt to deprioritize the alliance as a coordinating vehicle for U.S. security policy in the north Atlantic. A greater U.S. role in screening foreign investments in Greenland could also be a source of tension if the United States comes to be perceived as preferencing its own companies, instead of merely seeking to keep adversarial states out. Finally, there is always a chance that future disputes between the White House and NATO members could jeopardize the agreement in its current form. The Trump administration’s willingness to revisit agreements it negotiated does not necessarily engender confidence that the existence of a framework on paper means Greenland’s status is a settled matter in Washington’s eyes.

In a best-case scenario, durable U.S. defense engagement with Greenland paves the way for a broader NATO role in the territory. However, much will depend on the implementation of the agreement in the coming months and years.

Q3: What does the deal mean for missile defense and Golden Dome?

A3: From the Cold War to the modern day, Greenland has been a vital arm of U.S. homeland defense architecture. In the 1950s, the Distant Early Warning Line program erected a string of radar stations stretching from Alaska through Canada and Greenland to detect Soviet nuclear-capable, long-range bombers. With the advent of intercontinental ballistic missiles whose launch trajectories took them over the Arctic, Greenland’s importance grew again as a linchpin in U.S. and allied early warning systems. Thule Air Base in particular saw continued modernization and expansion of its missile detection capabilities throughout the Cold War.

At a minimum, the deal serves as an important signal of U.S. interest in carving out a greater role for Greenland in homeland defense. As missile threats evolve from ballistic systems to more maneuverable platforms such as hypersonic glide vehicles and cruise missiles, a rethink of the requirements for sensors and air defenses will be necessary in order to protect North America. The construction and expansion of new bases at Narsarsuaq and Mestersvig in particular offer opportunities for the United States, Denmark, and Greenland to expand the range of sensors and capabilities hosted in Greenland.

Historically, Greenland’s role has primarily emphasized the detection and tracking of adversary activities, at sea, in the skies, and in outer space. The United States relies on other systems, such as the ground-based interceptors based out of Fort Greely, Alaska, to handle the physical interdiction of incoming air and missile threats. The new agreement does make mention of the “establishment of a Golden Dome defense system,” which could open the door for the installation of more kinetic interception systems in Greenland. However, more information is needed to determine the precise role the United States envisions for Greenland as part of Golden Dome.

Q4. What does this mean for Canada and U.S.-Canada relations?

A4: The agreement mends a rift in North American, Arctic, and transatlantic relations that presented a considerable threat to Canadian security interests and North American cohesion. Greenland was the backdrop for Prime Minister Mark Carney’s attention-grabbing Davos speech in January and its proposed geopolitical reorientations. Canada could not help but look on with concern when an immediate neighbor, Inuit-majority country, and fellow NATO member was threatened with U.S. annexation and the severe disruption to North American defense cooperation it would have entailed.

Canada did not remain static over this period. It took a host of small steps, including opening a consulate in Nuuk and forging a new Canada-Denmark strategic partnership. Canada maintained or increased the operational pace in exercises that included both U.S. and Danish forces, such as the North American Aerospace Defense Command’s (NORAD) Noble Defender, its own Operation NANOOK, and NATO’s Arctic Shield and Northern Viking. Cumulatively, these have added up to more than the sum of their parts in terms of visibility and signaling. Moreover, Canada has hard assets that are of immediate use in augmenting Greenland’s security, such as the Canadian Coast Guard’s substantial icebreaker fleet and the Royal Canadian Navy’s ice-capable Arctic and Offshore Patrol Ships (AOPS). The incoming fleet of CP8A Poseidon maritime patrol aircraft next year will augment that toolset, as will Canada’s new submarine fleet beginning in the mid-2030s.

Overall, the agreement benefits Canada, in at least four ways:

1. It opens more space for U.S.-Canada cooperation on initiatives such as Golden Dome and maritime security.
2. It strengthens NATO’s centrality in Arctic defense and security, vindicating Canada’s own embrace since 2024 of a NATO Northern Flank
3. The inclusion of maritime issues in the agreement can buttress Canada’s evolving presence at sea, where the decision last year to give the Canadian Coast Guard a maritime security role is already bearing fruit.
4. Greenland’s very clear role in defining the agreement’s clauses implicitly reinforces the role of Indigenous governance in securing the Arctic, a strategic position where Canada brings a lot to the table and is essential to defending the Arctic.

These benefits, however, must be set against the real constraints stemming from the deterioration in overall U.S.-Canada political and trade ties. A close reading of the document will give Canadian officials pause due to its multiple references to the “American” rather than the “North American” continent, another unfortunate geographic rebranding that implies a diminishment of the agency of the United States’ closest neighbors. It is further evidence that the politics for a “Fortress North America” are not in place and that only a “Fortress America” is likely to be on offer from the Trump administration. The politics of the U.S.-Canada relationship will remain tetchy.

But overall, the document is a NATO-first rather than an “America First” document, and that is good news for U.S.-Canada Arctic cooperation. That puts the onus on Canada to build up operational options and capacity that can feed into a better political relationship when it becomes available. Intensified operations can allow Canada to deepen relationships with the U.S. military and Coast Guard in the meantime, while also evolving U.S.-compatible cooperation with Greenlandic civilian authorities, Denmark’s diplomats and armed forces, the other Nordic countries, and the European Union and NATO.

Most valuably, the agreement gives Canada a lodestone and a resource to build up a diversified set of relations in the Arctic within NATO that will ultimately strengthen U.S.-Canada ties. Informed by the agreement’s parameters, Canada can develop a heightened role in Greenlandic security and in the Atlantic Ocean, a role that will create new potential for a stronger U.S.-Canada dynamic in the Arctic, NORAD, and NATO once the overall relationship settles into a new normal.

Q5: Where should the U.S.-Canada-Greenland partnership go next?

A5: The next step should be to translate the new political accommodation over Greenland into sustained operational cooperation across the North American Arctic. Rather than creating a separate minilateral institution, Washington, Ottawa, Copenhagen, and Nuuk should use existing bilateral, NORAD, and NATO relationships to build a more integrated Arctic security architecture. This would build on the agreement’s renewed emphasis on NATO and create practical opportunities for Canada to contribute capabilities to Greenland’s security while strengthening its relationship with the United States.

The most immediate opportunity entails improving domain awareness and maritime security. Greenland occupies a critical position along the northern approaches to North America and the North Atlantic, while Canada can contribute icebreakers, AOPS, maritime patrol aircraft, surveillance capabilities, northern infrastructure, and eventually submarines. The four partners should increasingly connect their capabilities through information sharing, maritime surveillance, search and rescue, logistics, and common operating pictures. Greenland’s expanded defense infrastructure could consequently become part of a broader network stretching from Alaska across the Canadian Arctic to Greenland and onward into the North Atlantic. The priority should be interoperability, ensuring sensors, forces, ports, airfields, communications systems, and logistics networks can support one another during a crisis.

Cooperation should also extend beyond traditional defense. Critical minerals, ports, telecommunications, energy infrastructure, and trusted investment are increasingly part of Arctic security. The four governments could therefore develop a complementary economic security agenda that strengthens infrastructure resilience while limiting strategic dependencies on China and Russia.

Finally, Greenland, along with Denmark, must remain a participant rather than simply the territory on which North American defense takes place. Canada is particularly well positioned to support this approach given its own Arctic experience and Inuit connections across the Davis Strait. The strategic objective should ultimately be to stop treating Alaska, the Canadian Arctic, and Greenland as separate security spaces. The emerging missile, maritime, space, and economic challenges transcend those boundaries. The agreement therefore offers an opportunity to build a more coherent North American Arctic architecture—with NORAD at its continental core, NATO connecting it to the North Atlantic, and Greenland, the Kingdom of Denmark, Canada, and the United States providing the capabilities and partnerships necessary to make it work.

Christopher Hernandez-Roy is acting director and senior fellow in the Americas Program at the Center for Strategic and International Studies (CSIS) in Washington, D.C. Alex Dalziel is senior fellow for Arctic geopolitics at the Centre for Strategic Statecraft. Henry Ziemer is a fellow in the Americas Program at CSIS. Otto Svendsen is an associate fellow with the Europe, Russia, and Eurasia Program at CSIS.