This article summarizes the recent CNA event, “Basing Rights and Contested Sovereignty in Greenland and Diego Garcia.”


As Washington eyes a new era of great power competition, ongoing changes in sovereignty politics and decolonization could risk U.S. basing rights at two key military facilities: Thule Air Base in Greenland and Naval Support Facility Diego Garcia in the British Indian Ocean Territory. Both bases reside in territory held by U.S. allies; Greenland is part of the Kingdom of Denmark, and Diego Garcia is the largest island in the British Indian Ocean Territory. The status of either or both bases could change. Earlier this year, the International Court of Justice issued an advisory opinion that Britain should cede Diego Garcia and the rest of the Chagos Islands to Mauritius. Full independence from Denmark is a central political issue in Greenland.

Naval Support Facility Diego Garcia and Thule Air Base remain incredibly valuable to U.S. interests. Diego Garcia’s central location in the Indian Ocean will continue to be a vital site for the United States’ ability to conduct operations in the Indian Ocean, especially as China increases its activities here. In the case of Thule, the Greenland-Iceland-U.K. gap is a vital strategic choke point. Russia’s submarine-launched cruise missiles and the importance of transatlantic seafloor cables give Russian submarines real reasons to try to slip into the Atlantic — and give the U.S. and its allies compelling reasons to maintain bases in both Iceland and Greenland for antisubmarine aircraft patrols.

Engaging with local populations and acknowledging their sovereignty ambitions can help ensure continued access to these critical bases. The U.S. should speak directly with the governing bodies in Greenland and Mauritius and demonstrate the economic value of these bases to local populations.

Supporting the international rule of law — even when it goes against allies and complicates U.S. basing imperatives — has an additional benefit. The U.S. will increase its own credibility around other international legal disputes. For instance, the U.S. has been taking issue with the use of the International Court of Justice in the dispute between Mauritius and the U.K. over the Chagos Islands. But this appears to be in tension with the U.S. endorsement of using the Permanent Court of Arbitration to evaluate the Philippines’ dispute with China’s claims in the South China Sea.

Greenland and Diego Garcia are key enablers of U.S. military missions. Washington will need to balance the strategic and operational advantages gained from such access with its diplomatic and legal commitments to uphold international law and norms. Engagement with local populations and demonstrated economic benefits for the host countries could help ensure U.S. basing rights in these vital locations.