President Trump’s escalating insistence that the United States must “own” Greenland has pushed NATO into one of the gravest crises in its history, raising the extraordinary prospect that Washington could effectively force allies to choose between preserving the transatlantic alliance and acquiescing to an American bid for territory that belongs to another member state. What began years ago as an almost flippant idea has hardened into a strategic ultimatum that senior European officials now openly describe as a potential breaking point for the alliance built to prevent exactly this kind of great‑power coercion among Western democracies.

At the core of the standoff is a stark proposition reportedly voiced by Trump in private and hinted at in public: if NATO partners, and Denmark in particular, will not facilitate U.S. control over Greenland, Washington may be prepared to sideline, hollow out, or even abandon the alliance. Denmark and Greenland have categorically rejected any sale, transfer, or forced takeover, while a growing chorus of European governments warns that if the United States resorts to military means, NATO as a mutual defense pact would not survive.

The Greenland question is no longer about a real estate deal; it has become a test of whether NATO can withstand a scenario its founders never seriously contemplated—an attempted annexation by its own leading member of another ally’s territory.

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From curiosity to ultimatum

Trump’s fixation on Greenland is not new. During his first term, he floated the idea of purchasing the Arctic island, treating it as a bold, if unconventional, extension of American power. When Denmark swiftly dismissed the notion, many leaders viewed it as a diplomatic irritant rather than a strategic crisis.

That changed after Trump’s reelection. According to analysis from the Atlantic Council, the president began speaking of Greenland not as a speculative opportunity but as an “absolute necessity” for U.S. national security—and pointedly refused to rule out the use of military force to secure it. He framed the issue bluntly: “We need Greenland from the standpoint of national security,” arguing that Denmark could not adequately protect the territory and suggesting that Washington might pursue it “the hard way” if diplomacy failed.

In parallel, the White House rebuffed Copenhagen’s attempts to defuse the issue through conventional means. Denmark has indicated that the United States is welcome to increase troop numbers at Thule Air Base or even open additional facilities, while Greenland has signaled it is “open for business” to U.S. companies. Yet the administration has rejected these offers, reinforcing European perceptions that the goal is not better access or presence—but outright control.

The internal process in Washington underscores this shift. Diplomats report that responsibility for the Greenland portfolio sits not with the National Security Council’s Europe directorate but with its Western Hemisphere director, Michael Jenner, reflecting a deliberate decision to frame Greenland as part of a hemispheric strategy rather than a European security issue. Advisers describe this as an extension of a so‑called “Donroe Doctrine,” a conceptual framework that envisions firm U.S. control over the broader neighborhood, with Greenland folded into that “backyard.”

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Europe draws a red line

If the Trump team sees Greenland through a hemispheric lens, Europe sees it as a matter of core sovereignty and alliance credibility.

Greenland, an autonomous territory within the Kingdom of Denmark, has its own government and parliament but relies on Copenhagen for foreign and defense policy. All five of Greenland’s political parties have jointly rejected any idea of U.S. acquisition or military seizure, stating that “Greenland is not for sale” and that “no other country can interfere” in determining its future. Prime Minister Jens-Frederik Nielsen has been unequivocal: Greenlanders “are not interested in voluntarily becoming part of the United States.”

Denmark’s position is equally firm. Prime Minister Mette Frederiksen has publicly warned that an American attack or forced takeover of Greenland “would mark the end of NATO,” stressing that such a move would halt “everything, including NATO, and thus the security that has been established since the end of the Second World War.” Danish defense intelligence has gone so far as to list the United States—its closest ally for decades—as a concern in national security assessments, explicitly because of Washington’s stance on Greenland.

European governments have rallied quickly. Nordic and Baltic capitals were among the first to affirm that Greenland “belongs to the Greenlanders,” followed by a joint statement from France, Germany, Italy, Spain, Poland, Denmark, and later the United Kingdom supporting Greenland’s sovereignty. Canada, another key NATO ally and Arctic state, has also taken an unusually pointed stance, explicitly backing Greenland and opening a consulate there to deepen ties.

Behind the scenes, NATO Secretary General Mark Rutte faces what one analysis describes as a “nightmare scenario”: the possibility that the alliance’s leading member might use its military power to annex part of another ally’s territory. The very first paragraph of the North Atlantic Treaty commits members to resolving disputes by peaceful means and to refraining from the threat or use of force in ways inconsistent with the United Nations Charter. A U.S. military move on Greenland would contradict that foundational pledge.

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Why Greenland matters so much

The fight over Greenland is not only symbolic. Strategically, the island sits at the junction of the North Atlantic and Arctic Oceans, directly astride key air and sea routes between North America, Europe, and the High North.

For the United States, three main factors drive interest:

– Military positioning: Thule Air Base already houses critical early‑warning and missile‑tracking infrastructure. As Arctic sea ice recedes, control of Greenland’s approaches becomes more central to missile defense, undersea warfare, and the monitoring of Russian activity.

– Resource potential: Greenland is believed to hold significant reserves of rare earth minerals, hydrocarbons, and other raw materials that could become more accessible as the climate warms. Former National Security Advisor Mike Waltz has emphasized access to these resources as a key U.S. interest.

– Arctic competition: Trump has repeatedly cited the presence of “Chinese and Russian ships everywhere” around Greenland, using these claims to argue that Denmark cannot protect the island adequately. NATO officials acknowledge that Russian and Chinese activity in the Arctic is a genuine concern and say the alliance is stepping up surveillance, patrolling, exercises, and training across the High North.

Yet many European officials and analysts argue that these security and resource arguments do not justify the administration’s fixation on acquisition. If the U.S. objective were simply to bolster defense or investment, they note, Washington could accept Denmark’s offer for more bases and presence, or encourage American companies to invest—options Copenhagen and Nuuk have both welcomed. Instead, the insistence on sovereignty has led some to conclude that the administration’s logic is ideological or imperial rather than strategic in the usual sense, prompting accusations of “American imperialism” from former Danish diplomats.

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A NATO crisis unlike any before

The Greenland confrontation exposes a structural vulnerability inside NATO that many policymakers never expected to confront: the possibility of intra‑alliance coercion or conflict. The alliance’s collective defense clause, Article 5, is designed for external threats—an attack by Russia or another adversary—not for a scenario in which one member threatens another.

As Denmark’s former NATO ambassador has pointed out, if an outside power attacked Denmark, Article 5 would almost certainly be triggered; allies would be obligated to come to Copenhagen’s defense. But if the attacker is NATO’s most powerful member, the situation is fundamentally different. In that case, he argues, “NATO could not engage because it’s a conflict inside NATO and not between NATO and a foreign power.”

This logic reveals the depth of the alliance’s dilemma. If the United States were to use force against Greenland:

– Article 5 would be hollowed out. NATO’s core promise—that an attack on one is an attack on all—would effectively be suspended for the alliance’s own largest member. As Norwegian Foreign Minister Espen Barth Eide has put it, “The idea of NATO will be broken if the US takes Greenland.”

– Extended deterrence would collapse. Russia, China, and other rivals would quickly understand that the alliance could not credibly claim unity or mutual defense in Europe and Canada if its leading power had just overridden those very principles. They might feel emboldened to test NATO’s resolve elsewhere, undermining stability across the Euro‑Atlantic region.

– An ally would be permanently alienated. Denmark has been a loyal U.S. partner, contributing heavily to the NATO mission in Afghanistan and later to Ukraine-related efforts. An American invasion of Greenland would rupture that relationship and send a clear warning to other medium‑sized allies that their security within NATO is conditional, not guaranteed.

The Atlantic Council warns that such a scenario would be “NATO’s darkest hour,” arguing that the alliance’s essence would be lost even if its formal structures survived on paper. The damage would not be limited to Europe; Canada and other allies, dependent on U.S. bases and cooperation, would be forced to reconsider the reliability of American security guarantees.

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The domestic and diplomatic pushback in the U.S.

The Greenland push has not gone unchallenged inside the United States. Some senior officials, including Secretary of State Marco Rubio, are reportedly working quietly to de‑escalate the crisis and seek a negotiated outcome, suggesting that the overt military threats are at least partly designed as leverage. In private meetings, Rubio has signaled to lawmakers a preference for diplomacy, implying that force is a last resort rather than a predetermined path.

On Capitol Hill, bipartisan unease is growing. Senator Rand Paul, a Republican often aligned with Trump on foreign policy restraint, has stated that he will “do everything to stop any kind of military takeover of Greenland,” arguing that such a move would be reckless and strategically counterproductive. Other lawmakers—concerned about the legal, ethical, and alliance implications—have pressed the administration to clarify its commitments to NATO and the principles of the UN Charter.

Former U.S. officials and scholars have also weighed in. Analysts such as Michael McFaul have characterized the idea of invading Greenland as one of Trump’s “worst” strategic ideas, noting that it would sacrifice a successful, decades‑long alliance for an unnecessary territorial gambit and permanently harm U.S. global credibility.

Yet Trump and his closest advisers remain convinced that the United States holds key leverage. European dependence on U.S. military power, especially in nuclear deterrence and high‑end conventional capabilities, has allowed Trump to force concessions on defense spending in the past; some in the White House believe the same hardball tactics can eventually move Europe on Greenland. As one former NSC official supportive of Trump’s approach put it, the administration now has an “intellectual framework” for the entire hemisphere and “they’re going to tie Greenland into that.”

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NATO scrambles to shore up the Arctic flank

Caught between deterring external rivals and managing an internal crisis, NATO has begun to reinforce its Arctic posture in a way that simultaneously addresses Trump’s stated security concerns and signals support for Denmark and Greenland.

Alliance officials describe expanding surveillance, patrols, military exercises, and training in the High North, both to respond to genuine Russian and Chinese activity and to demonstrate that Greenland’s security can be strengthened without changing its sovereignty. Some European capitals have even floated the idea of deploying European forces to Greenland as a show of solidarity with Denmark, though Copenhagen has so far declined such offers to avoid further inflaming tensions with Washington.

This dual‑track approach—meeting Trump halfway on Arctic security while refusing to legitimize territorial demands—reflects a broader European strategy: maintain NATO if at all possible, but begin planning for a future where Europe must provide for more of its own defense. Former Danish officials and NATO planners increasingly speak of a “more European NATO” or alternative defense frameworks should the United States step back or cross the line in Greenland.

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From ally to adversary?

The Greenland crisis has crystallized a deeper rift over what NATO is for in the 21st century. For most European governments, the alliance is an institutionalized commitment to collective defense, democratic solidarity, and a rules‑based order in which borders cannot be changed by force among members. For Trump, NATO is often framed more as a transactional instrument—valuable when it compels allies to spend more or support U.S. strategic priorities, expendable when it constrains American freedom of action.

By implying that it may be a “choice” between NATO and acquiring Greenland, Trump has inverted the logic of the alliance’s founding. The United States once championed NATO to prevent great‑power coercion in Europe and to guarantee that smaller states would not be bullied by larger ones. Today, in the Greenland showdown, the United States is seen by many of its closest partners as the would‑be bully—and Greenland, backed by Denmark, as the small democracy resisting pressure.

The stakes are therefore larger than the island itself. If Washington ultimately backs away from any use of force, accepts Greenlandic and Danish sovereignty, and works through NATO to strengthen Arctic security, the alliance may emerge battered but intact—its norms strained but not broken. If, however, the administration acts on its most extreme rhetoric, the result could be the effective end of NATO as it has existed since 1949 and the birth of a much colder, more fragmented security order in Europe.

For now, Copenhagen, Nuuk, Brussels, and Washington remain locked in a tense diplomatic contest over the future of a vast, icy territory that has suddenly become the fault line of the transatlantic order. Whether the alliance survives may hinge on whether a U.S. president is ultimately willing to subordinate his Greenland ambitions to the broader strategic value of keeping friends, rather than forcing them to choose between their territory and their treaty.

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