News24 | Has Mauritius lost its agency in the Chagos deal?

A US Air Force B-1B bomber takes off from the Diego Garcia base on a strike mission against Afghanistan on 07 October 2001, during Operation Enduring Freedom.

USAF/DOD/AFP via Getty Images

By offering Britain a 99-year lease to secure decolonisation, Mauritius bound its sovereignty to the shifting priorities of great powers, writes Timothy Walker in ISS Today.

It seemed a done deal. Mauritius would acquire sovereignty over the Chagos Archipelago while granting Britain extensive rights over Diego Garcia island for 99 years, allowing the United States (US) military base there to continue operating. The May 2025 agreement would replace a colonial arrangement with one founded on Mauritian consent, while giving Britain and the US the long-term security guarantees they craved.

But the treaty’s implementation has stalled since the necessary legislation failed to pass in Britain’s Parliament. The US had withdrawn its earlier support amid tensions with London over Greenland and Britain’s refusal to authorise the island’s use for offensive operations against Iran. On 23 September, Britain’s Defence Secretary Wes Streeting acknowledged that the agreement could not proceed without US backing.

In 2025, the deal appeared to mark the culmination of a largely successful Mauritian diplomatic and legal campaign. Yet the current paralysis raises questions about the government’s diplomatic decision making and remaining options, particularly as domestic political and economic pressures intensify.

The impasse also exposes Mauritius’ limited influence over implementation. Although the country secured British recognition of its sovereignty, Mauritius remains dependent on decisions in and between Britain and the US.

Mauritius is not without diplomatic and legal options, and its government recently raised the possibility of pursuing the latter. Legal action could reinforce its sovereignty claim, clarify Britain’s obligations and increase international pressure for implementation.

Mauritius’ decades-long campaign against British administration of Chagos proved remarkably effective when framed around decolonisation and international law. It secured widespread global support, including from India and the African Union, and ultimately persuaded Britain to negotiate a settlement.

But Mauritius cannot compel the US to accept revised operating arrangements or guarantee ratification by Britain’s Parliament. Nor is it certain that any concessions would secure the decolonisation that Mauritius spent years pursuing. The deal painstakingly negotiated between Britain and Mauritius reconciled competing priorities: decolonisation, preserving the military base, strengthening bilateral relations and accommodating their respective strategic partners.

Short of abandoning its sovereignty claim, Mauritius effectively offered the US what it sought: legally established, long-term security for its Diego Garcia operations. Yet US President Donald Trump’s administration obstructed the final stages of British implementation, raising the question: why has Washington become unwilling to accept a settlement designed largely to protect its own interests?

Mauritius’ room for manoeuvre is constrained partly by its longstanding willingness to align with US interests. Having repeatedly affirmed its support for the Diego Garcia base’s continued operation, Mauritius would find it difficult to reverse course without jeopardising diplomatic relationships and benefits.

Yet this allowance has not secured Trump’s backing. Instead, it has trapped Mauritius in a paradox: by accommodating US security interests, it surrendered its leverage, leaving completion of its decolonisation at the mercy of Washington’s shifting priorities.

The Chagos Archipelago

The challenge is further complicated by Diego Garcia’s heightened value for long-range military operations, logistical support and sustaining the US blockade on Iran. Iranian attacks on US bases in the Gulf, especially the US naval base in Bahrain, have reinforced the importance of Diego Garcia, which is situated beyond the immediate range of Iranian missiles.

Although Iran’s capacity to seriously damage Diego Garcia remains unclear, the possibility of increased escalation and maritime disruption in the Indian Ocean reinforces Washington’s interest in preserving secure facilities further afield.

Diego Garcia’s importance also extends beyond the present conflict. The vulnerability of the US’ forward-deployed facilities, so close to Iran, and growing uncertainty over future host-country access, could encourage greater US reliance on remote island installations such as Diego Garcia and Guam in the Pacific Ocean.

Diego Garcia’s distance from the immediate Iranian threat provides a secure location for a wide range of continued long-range US operations. Yet this military power projection still depends on agreements with Britain for access.

Future US administrations may seek to restore allied relationships and secure a durable legal framework for the base. But the structural reasons for US interest in Diego Garcia will remain, and its established infrastructure would be hard to replace.

Three competing races against time are now underway.

The first is fiscal. The Iran war has added to Mauritius’ import costs and inflationary pressures, exacerbating longstanding fiscal difficulties, including high public debt. The government and International Monetary Fund identified treaty payments as a source of revenue to accelerate debt reduction. Their absence complicates fiscal planning, but the state cannot be seen to be focusing on revenue shortfalls rather than decolonisation.

The second race against time is diplomatic. One potential advantage for Mauritius is the 2036 expiry of British-US arrangements governing Diego Garcia. First concluded in 1966 and extended for 20 years in 2016, the agreements have been amended before. A revised version was reportedly prepared following negotiations, but Trump’s opposition has prevented progress.

Future US administrations may prove more receptive to the settlement, particularly if relations with Britain improve. A direct Mauritius-US agreement is also legally conceivable and something Mauritian authorities have always offered, but would be diplomatically difficult with Britain’s existing arrangements in place.

The third race affects displaced Chagossians. Dispersed between Britain, Seychelles and Mauritius, the community remains divided over the treaty and terms of return, while competing political and legal campaigns complicate efforts to secure a common position. The landing of activist Misley Mandarin and other Chagossians on Île du Coin in the Chagos Archipelago in February, followed by litigation and British court rulings, introduced further legal complications.

For many surviving members of the Chagossian generation forcibly displaced from the archipelago, the opportunity to return safely is diminishing with age. Further delays may extinguish the possibility of returning to their homeland in their lifetimes.

Timothy Walker is a Consultant at the Institute for Security Studies (ISS) in Pretoria.