Despite this transfer, the UK and the United States will retain the right to operate a military base on Diego Garcia, the largest island in the group, for an initial 99-year lease.
The UK is poised to sign a landmark agreement transferring sovereignty of the Chagos Islands to Mauritius, while securing continued operation of a vital UK-US military base for nearly a century. The deal, due to be formalised, reflects years of complex negotiations and geopolitical pressures surrounding the strategically significant Indian Ocean archipelago.
Prime Minister Sir Keir Starmer will join a virtual signing ceremony with representatives of the Mauritian government, officially handing over sovereignty of the British Indian Ocean Territory (BIOT) to Mauritius. Despite this transfer, the UK and the United States will retain the right to operate a military base on Diego Garcia, the largest island in the group, for an initial 99-year lease. This arrangement will be backed by a multi-billion-pound financial package, although the precise cost to British taxpayers remains undisclosed.
The Chagos Islands deal has been in the making for several years, but encountered delays due to changes in leadership in both Mauritius and the United States. Originally announced in October 2024 during negotiations with then Mauritian Prime Minister Pravind Jugnauth, progress stalled after elections saw Navin Ramgoolam replace Jugnauth. Ramgoolam reportedly raised concerns over the terms, prompting fresh discussions.
In the US, the election of Donald Trump also slowed momentum, as his administration took time to review the agreement. Initially, prominent Republicans including Senator Marco Rubio voiced strong objections, warning that the deal posed a “serious threat” to US national security. Their concerns centred on Mauritius’s growing relationship with China, which could potentially compromise the strategic military base’s security.
Despite the initial opposition, Trump indicated last month that he would support the deal, paving the way for finalisation.
The British Foreign Office emphasised the importance of safeguarding the joint UK-US military presence on Diego Garcia, describing it as “vital to our national security.” In parallel with the signing, representatives from the Chagossian community—the displaced inhabitants of the islands—have been invited to meet Stephen Doughty, Minister for Europe, North America and Overseas Territories. This meeting will involve six delegates from three separate Chagossian groups and aims to discuss ongoing projects and the formation of a new Chagossian contact group.
The Chagos Archipelago was separated from Mauritius in 1965 while the island nation was still a British colony. The UK purchased the islands for £3 million, but Mauritius has long contested the legitimacy of the separation, arguing it was forced to relinquish control as a condition for independence in 1968. International pressure has grown on the UK to return sovereignty. Various United Nations bodies have sided with Mauritius’s claims, intensifying calls for decolonisation of the territory. The last Conservative government opened negotiations on the matter in late 2022 but later criticised the Labour administration’s willingness to transfer the islands.
Reform UK has also expressed strong opposition to the deal. In contrast, Labour maintains that formalising the handover while securing a long-term lease for the military base is the best way to protect UK national security interests. Defence Secretary John Healey recently underlined the base’s essential role in UK and US security cooperation.
“We’ve had to act, as the previous government started to do, to deal with that jeopardy. We’re completing those arrangements and we’ll report to the House when we can,” Healey said in the House of Commons this week.
Following the signing, MPs will be briefed on the agreement’s details, including potential provisions for a 40-year extension of the military base lease. The UK’s commitment to maintaining its strategic foothold in the Indian Ocean will thus remain intact, even as sovereignty transfers to Mauritius.
This historic deal represents a complex balancing act—addressing the longstanding sovereignty dispute while ensuring Britain’s security interests remain protected in an increasingly volatile geopolitical landscape. It also marks a significant moment in UK-Mauritius relations and broader efforts to resolve colonial-era territorial disputes through diplomacy.
As negotiations conclude, all eyes will be on the UK government’s ability to deliver a deal that honours international law, respects the rights of the Chagossian people, and preserves the strategic imperatives critical to Western security alliances.
