Mauritius gives Britain until July to finalize Chagos Islands deal

The end-of-July deadline has turned the Chagos talks into a test of whether Britain can reconcile decolonization with the hard realities of U.S. military power in the Indian Ocean. Mauritius has told London it will wait only until the end of July 2026 to finalize the transfer of the Chagos Islands, a deal that would hand sovereignty to Mauritius while keeping the Diego Garcia base in operation.

The timing matters because the agreement, signed by Britain and Mauritius on May 22, 2025, was meant to produce a “full and final resolution” of the sovereignty dispute. It was also designed to preserve the long-term secure operation of Diego Garcia, the six-atoll archipelago’s most strategically sensitive site. The treaty text was still not in force when published, and a later pause in London, prompted by objections from Donald Trump’s administration, left the ratification process incomplete.

A British delegation has now met Mauritian Prime Minister Navin Ramgoolam in the first talks since the pause. Mauritius Attorney General Gavin Glover said the government had no visibility on whether U.S. approval would ultimately come through, while Foreign Minister Dhananjay Ramful said on April 11 that Mauritius would “spare no effort” to reclaim the islands and pursue diplomatic or legal avenues. Mauritius has also said the key unresolved issues include the marine protected area, security, resettlement and the trust fund.

The deal’s financial and military structure underscores why the negotiations have become so difficult. The House of Lords International Agreements Committee said Britain would pay Mauritius an average of £101 million a year for 99 years, or about £3.4 billion in 2025/26 prices. Reporting on the package said it also included a 99-year lease for Diego Garcia, with an option for a 40-year extension, a framework intended to secure the base’s future for generations.

The sovereignty dispute reaches back to the colonial separation of Chagos from Mauritius. In its advisory opinion of February 25, 2019, the International Court of Justice summarized the case as involving the detachment of the archipelago from Mauritius, the creation of the British Indian Ocean Territory and the forcible removal of the population. Human Rights Watch says the expulsions of Chagossians began in the late 1960s after Britain and the United States agreed to build the Diego Garcia base.

Mauritius’s deadline now puts pressure on London to decide whether the agreement can still move ahead with U.S. objections unresolved. If it cannot, the island nation has signaled it will move on to its next step, leaving one of the Indian Ocean’s most consequential sovereignty disputes still unsettled.