NATO’s Unity Tested by U.S.–Greenland Dispute as Trans-Atlantic Strain Deepens

A geopolitical confrontation between the United States and its European allies over Greenland’s sovereignty — driven by U.S. President **Donald Trump’s demand that Washington assume control of the Arctic island — has sparked one of the most serious crises facing the North Atlantic Treaty Organization (NATO) since its founding. NATO, long regarded as the cornerstone of Western collective defence, now finds its cohesion under intense pressure from within its own ranks. 

A Rift Over Greenland’s Future

President Trump has renewed a controversial bid for U.S. control of Greenland, an autonomous territory of the Kingdom of Denmark, citing what he describes as strategic imperatives — including countering alleged Russian and Chinese influence in the Arctic. He publicly stated that such a move “will be done,” framing it as a necessary step for national and allied security. 

Trump also threatened to impose tariffs on several European NATO members — including Denmark, France, Germany, the UK, Sweden, Norway, the Netherlands and Finland — unless an agreement on purchasing Greenland is reached. These levies were initially set at 10% from February 1, rising to 25% by June unless Greenland’s ownership changes hands. 

The proposal has been firmly rejected by Danish and Greenlandic officials, who stress the island should remain part of Denmark and continue to be defended under existing NATO arrangements, including the mutual defence guarantees of Article 5. Greenland’s leaders have called for continued multilateral protection through NATO, reinforcing that decisions on sovereignty should rest with its people under international law. 

European Pushback and Trans-Atlantic Tensions

European governments have condemned the U.S. approach as coercive and destabilising. Joint statements from EU and NATO member states emphasise solidarity with Denmark and a commitment to uphold sovereignty and international norms. Leaders warn that tariff threats — perceived as economic “blackmail” — could spark a “dangerous downward spiral” in relations between the West’s leading democracies. 

In response, European Union officials are considering using the bloc’s Anti-Coercion Instrument, a powerful trade defence mechanism designed to counter hostile economic measures, and even preparing broad retaliatory tariffs worth tens of billions of euros against U.S. goods. 

Senior European politicians have stressed that threats or forced territorial change among NATO allies would violate the alliance’s core principles and could have “severe political consequences,” undermining decades of trans-Atlantic cooperation. 

NATO’s Existential Question

Analysts and officials have warned that this standoff is not just a trade dispute but a fundamental test of NATO’s unity and credibility. If a member—particularly the military alliance’s most powerful—seeks to alter the territorial integrity of another through pressure or implied force, it could set a precedent that shakes the foundation of collective defence cooperation. Danish Prime Minister Mette Frederiksen stated explicitly that military aggression by one ally against another would effectively spell the end of NATO as it has operated since World War II. 

The crisis underscores a broader anxiety: that alliance cohesion cannot be taken for granted when strategic interests, domestic politics and unilateral pressure tactics collide. For countries outside the alliance, including those in Africa, a fracturing NATO — long a guarantor of global stability, deterrence against aggression, and coordinated responses to security threats — would mark a profound shift in the international order.

Broader Implications

A breakdown in NATO unity over Greenland could reverberate far beyond the Arctic. It would signify a weakening of the rules-based security architecture that many nations rely on for defence cooperation, economic stability, and diplomatic predictability. In such a scenario, smaller states that depend on a stable Western alliance framework could face heightened uncertainty in regional security, aid partnerships, and trade relationships.

The Greenland dispute, emerging at a time of intense global competition and multipolar tensions, has therefore elevated what once seemed an unlikely quarrel into a defining geopolitical test for the trans-Atlantic alliance and the future of collective security.