How a Tiny Indian Ocean Island Could Force a US-UK Rift

Mauritius does not usually make headlines in the United States, but this small island state off the east coast of Africa could force the U.S. to rethink operations in the Middle East and Asia — and strategic policy around the globe.

The country has recently notched victories at the International Court of Justice and UN General Assembly in its battle to take from Britain its sovereignty of the Chagos Archipelago. The largest of these islands, Diego Garcia, has for decades been a key logistics, reconnaissance, and operational base for U.S. forces. While many factors are at play, including discussion about the Chagossian people, the Diego Garcia case reveals two critical dimensions that warrant attention by U.S. policymakers now.

The first is alliance management. The UK is arguably the United States’ closest alliance partner, given their strong diplomatic, military, and intelligence ties. So far, the Chagos dispute has been framed by the UK and U.S. governments as a bilateral dispute between the UK and Mauritius. The UK, which has claimed sovereignty over Diego Garcia and the wider Chagos Archipelago since 1814, recently reasserted this through a statement by the Foreign and Commonwealth Office. Washington supports its ally’s sovereignty claim. 

However, a UN General Assembly resolution in May 2019 found the UK, U.S. and a handful of other countries in a striking minority of world opinion on the issue. By a 116-6 margin, the UN General Assembly voted to support the ICJ advisory opinion that the UK leave the Chagos Archipelago. 

While the U.S. has many bilateral basing arrangements with allied and partner countries globally, the UK’s role in Diego Garcia is a complicating factor and has important implications for Washington’s management of its special relationship. Given the U.S. national interest in this strategically important military base, U.S. policymakers should consider whether there is a tipping point at which Washington would withdraw support for its closest ally’s colonial-era sovereignty claim and choose instead to work with Mauritius.

Indeed, the Mauritian government has offered terms to persuade the United States to do just that. At a recent event organized by CNA, Ambassador Jagdish Koonjul, permanent representative of Mauritius to the United Nations, announced that his country would permit the U.S. military to remain in Diego Garcia after a withdrawal by the UK. He even offered to lease the base to the United States for 99 years, far longer than the current deal for access through 2036. 

The second critical dimension to this issue concerns U.S. support for international institutions and legal norms. The ICJ advisory opinion asserts that efforts to ensure Mauritius’s decolonization fall within the remit of the UN General Assembly, while the UN General Assembly resolution “demands” that the UK withdraw from the Chagos Archipelago by the end of 2019. But the UK has neither renounced its claims nor left. This stance raises doubts about the utility of international institutions, especially in an era of great power competition where there are concerns about China’s and Russia’s respect for the rule of law. 

Washington will need to avoid the appearance of inconsistency in its commitment to the rule of law. In 2019, the State Department questioned the jurisdiction of the ICJ to decide cases where one state is not a participant. However, this position is possibly at odds with the State Department’s expression of strong support in 2016 for the rule of law in efforts to resolve disputes in the South China Sea, including through international arbitration, after a Hague decision in favor of the Philippines over China, even though China chose not to participate. Avoiding the appearance of such inconsistencies is vital for the U.S. to retain credible global leadership and contrast its behavior with great power rivals China and Russia. 

At present, both Mauritius and the UK appear determined to stick to their positions. Recently, the UN updated its map to no longer list UK control of the Chagos Archipelago. Given this and other legal developments, U.S. policymakers should adopt a strategic approach to Diego Garcia that carefully considers U.S. national interests with regard to global basing posture, alliance management with the UK, and the role of democratic norms and the rule of law in an era of great power competition. Beyond harnessing its military capabilities, the United States will need to advocate in the coming decades for its political, economic, and social model as superior to that of its great power competitors. Policy decisions that appear self-serving or unfair to minority populations—for which the U.S. has criticized both China and Russia—risk eroding the case for the primacy of the U.S. model.