Saving Greenland without NATO? The EU's little-known weapon.

Translated by Annachiara Laino

The possibility that the United States might use force to seize control of Greenland, raised more or less explicitly by Donald Trump, has reopened a question that Europe has always preferred to avoid: what happens if the threat to a member state's security comes from the main guarantor of Euro-Atlantic defense? In such a scenario, NATO (Danish security's pillar) would risk being politically paralyzed. This is where a little-known clause in the EU Treaties comes into play: Article 42.7, the Union's mutual assistance pact.

Inserted into the 2009 Lisbon Treaty, Article 42.7 establishes that if a Member State is the victim of armed aggression on its territory, other Member States are obliged to provide aid and assistance by all the means in their power, in compliance with Article 51 of the UN Charter. The wording is, from a legal and diplomatic perspective, surprisingly peremptory. Unlike NATO's Article 5, which leaves allies discretion (the measures they deem necessary), the European text explicitly speaks of an obligation. For this reason, some analysts consider it even more binding, at least formally.

However, the strength of language does not equate to the strength of capabilities. The EU does not have a common army or a truly integrated chain of command. As Alexander Mattelaer observed, the clause is stronger in diplomatic language, but relies on a much smaller force pool than NATO. In other words, Article 42.7 is a powerful political and legal signal, but still an incomplete operational tool.

Not surprisingly, the clause has been invoked only once in the history of the Union. In 2015, after the ISIS terrorist attacks in Paris, France asked its European partners for assistance. The response was unanimous but highly flexible: some states offered military support in external theaters such as Mali, allowing Paris to redeploy its forces within its own territory. The EU, lacking an army, functioned as a platform for political coordination rather than a direct military actor.

Applying this precedent to the Greenlandic case, however, raises new problems. Greenland, despite being an integral part of the Kingdom of Denmark, left the European Community in 1985. This has raised doubts about the territorial applicability of Article 42.7. According to the European Commission and Defence Commissioner Andrius Kubilius, these doubts are unfounded: Greenland falls within the territory of the Kingdom of Denmark and is therefore covered by the mutual assistance clause. This interpretation strengthens Copenhagen's position, but does not eliminate political uncertainties.

Invoking Article 42.7 would indeed be a highly politically risky decision. As Antonio Missiroli has emphasized, Denmark would be unlikely to proceed without the certainty of unanimous consent. Countries like Hungary could refuse to oppose Washington, effectively blocking any substantive response. Unanimity, which constitutes the clause's symbolic strength, is also its main weakness.

If the appeal succeeds, however, the consequences would be significant. Politically and legally, the EU would send an unprecedented message of solidarity, affirming that armed aggression against a member state, even if perpetrated by a historic ally, cannot go unanswered. Practically, options range from joint declarations and financial assistance to more forceful economic and diplomatic measures. Some MEPs have already evoked a catalogue of countermeasures: from the expulsion of US troops from European bases to a ban on US aircraft overflights and restrictions on access to the single market.

The possibility of an EU-US military conflict remains unanimously considered unrealistic. European military structures in Brussels are limited: a few dozen officials and a command capacity unlikely to exceed 3,000 men, primarily experienced in peacekeeping missions. However, nothing would prevent member states from providing bilateral military assistance to Denmark, using Article 42.7 as a legal and political framework.

The real impact, however, would be systemic. A forced annexation of Greenland by the United States would strip NATO of its political credibility, even if it did not automatically spell its legal end. As Fabrice Pothier observed, the Alliance would formally remain in existence, but it would lose its role as an impartial guarantor of European security. In that vacuum, the EU would be pushed to strengthen its own autonomous solutions, finally giving shape to Article 42.7.

This would imply a profound transformation of the European security architecture: greater military integration, clear procedures for mutual assistance, and perhaps a credible European operational command. It is no coincidence that Kubilius has proposed launching a debate on institutional defense readiness, with the aim of making Article 42.7 fully operational.

The paradox is clear. A crisis triggered by a historic ally could accelerate what has remained unfinished for decades: a European defense less dependent on Washington. Greenland, Europe's geographic periphery, thus risks becoming the symbolic center of a continental strategic shift.

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