In an unprecedented move last week, Denmark labeled its ally the United States as a potential security risk. A report by the Danish Defense Intelligence Service argued Washington is using its economic and military power to “assert its will,” creating new security risks for Europe and for Greenland, Denmark’s semi-autonomous territory.
NATO allies have been at odds before: Turkey and Greece clashed over Cyprus when Turkey invaded the island in 1974, Canada and Spain during a 1995 dispute over fishing rights. But the Danish report stands apart: It is one of the strongest warnings about the US to come from another member state.
How we got here. Concerns over Greenland’s sovereignty have escalated since US President Donald Trump took office. He has repeatedly insisted the island is critical for national security. Economic factors are at play too: Greenland is rich in rare earth minerals needed to manufacture much of today’s technology, from advanced batteries to military jets. The island’s position in the Arctic puts it in the middle of an international competition with Russia and China over shipping and deep sea mining. Trump has even refused to rule out taking Greenland by force, a stance that has strained relations between Copenhagen and Washington.
In August, Denmark summoned the head of the US Embassy in Copenhagen, alleging that three unnamed Americans with ties to Trump were running “covert influence operations” in Greenland. A few months later, reports emerged that Copenhagen had created a “night watch” alert unit in the spring, monitoring Trump’s comments while Denmark sleeps, checking signs of potential threats against the territory.
Still, diplomatic channels have remained open. Earlier this month, Greenland hosted annual meetings with American officials to discuss ties between the US, Greenland, and Denmark. Greenland’s Foreign Minister Vivian Motzfeldt emphasized that Greenlanders alone will choose their future. She added that the island was “pleased” to host talks, as a way to ensure the interests of both Greenlanders and Americans were respected.
What are the implications for NATO? The Danes are placing their dispute with Washington in the context of broader tensions between the US and Europe. The intelligence report warns the US is stepping back from its long-standing role as Europe's primary security guarantor, in part due to its growing focus on competition with China. That uncertainty, the Danes argue, could embolden Russia’s “willingness to intensify its hybrid attacks against NATO.” Allies like Poland and Romania have already reported repeated breaches of their airspace by Russian drones since the war in Ukraine began.
The report also comes on the heels of the new US National Security Strategy, which claims that Europe faces “civilizational erasure” within two decades and argues that the US must “cultivate resistance” inside Europe to counter the continent’s current trajectory. That language has further alarmed European capitals, including Copenhagen, deepening concerns about the future of the transatlantic alliance.
A test NATO has never faced. If the US were to use military action to gain control of Greenland, it could fracture the NATO alliance or trigger serious rifts that Russia or China could seek to exploit. Article 5 of the alliance’s charter states that an attack on one ally is an attack on all, requiring collective defense. But it has never been tested by aggression from a fellow member. In practice, Article 5 cannot be invoked by one NATO member against another without unanimous consent, which the US itself could block.
