Professor Jacques Hartmann

Greenland is not merely an Arctic outpost. It has become a test case for whether international law still constrains power among states.

The renewed US rhetoric about ‘getting’ Greenland marks a disturbing shift from eccentric diplomacy to open geopolitical pressure. When a US president refuses to rule out the use of force to acquire territory, the issue is no longer one of provocation but of law and the survival of the post-1945 international order.

Legally, the situation is clear: Greenland is not terra nullius, nor is it available for acquisition by purchase, pressure, or coercion. Sovereignty over Greenland has long been recognised internationally, including by the US itself. This recognition is embedded in treaties, confirmed by international adjudication, and reflected in more than a century of failed attempts by the US to buy the island.

What makes the current situation particularly paradoxical is that the US already enjoys extensive military access in Greenland. Since 1941, and under a revised agreement from 1951, the US has maintained a military presence in Greenland, today concentrated at Pituffik Space Base. This presence has always rested on Danish consent, and on the shared framework of NATO’s collective defence. The US has never claimed rights in Greenland independent of Danish sovereignty. On the contrary, its military agreements explicitly reaffirm it.

That context matters because it exposes the incoherence of current threats. The US is not excluded from Greenland. It is present there precisely because Denmark consented, within a rules-based international order.

The situation becomes even more legally charged if the US were to withdraw from NATO. The 1951 defence agreement governing US forces in Greenland is closely tied to NATO membership. While it does not automatically terminate if the US leaves NATO, such a withdrawal would undermine the very basis on which Denmark consented to a permanent US military presence.

Layered onto this is Greenland’s own constitutional position. Greenlanders are recognised as a people with a right to self-determination under international and Danish law. That right entitles them to decide on independence, not to be transferred between sovereigns under external pressure. Any attempt to bypass Greenlandic consent, or to manufacture it through economic or military coercion, would fly in the face of the rule of law.

The danger of the current rhetoric lies not only in the likelihood of annexation but also erosion of the post-1945 international order. If territorial integrity becomes negotiable when power disparities are large enough, then alliances, treaties, and the international legal order lose their meaning.

Professor Jacques Hartmann is chair of international law at the University of Dundee and a former legal officer at the Danish Ministry of Foreign Affairs, where he represented Denmark at diplomatic conferences and before the International Court of Justice.