UK-Mauritius Chagos Deal
Chagos Archipelago: What’s the Deal?
Despite the October 2024 deal that restored the Chagos Archipelago to complete Mauritian governance, continuing to lease control of Diego Garcia to the United Kingdom for 99 years, the return of President Trump to US leadership has delayed the final negotiation stages. Diego Garcia houses a critical American military base, and serves a vital military outpost, particularly as Chinese expansionist objectives in the South China Sea come closer to fruition. Its strategic location offers key oversight of the Malacca Strait and beyond.
Historical Context of the Archipelago
The potential return of Chagos to Mauritius follows decades of campaigning. France colonised Mauritius, including the archipelago, in 1715, but lost control to the British in 1814 after the fall of Napoleon and consequent concession of French overseas territories. Whilst the island nation secured independence from the UK in 1968, its sovereignty was conditioned on relinquishing control of Chagos. In a mass campaign of forced displacement between 1965 and 1973, the British government, under the guise of economic hardship, exiled local Chagossians to make way for military constructions and the lease of Diego Garcia to the United States. Diego Garcia was a key component of ‘War on Terror’ strategic operations, deploying aircraft to Afghanistan and housing suspected al-Qaeda members.
Minor legal challenges by displaced Chagossians contested British presence in the archipelago, but it wasn’t until 2010 that an official campaign for the return of the islands commenced, with Mauritian Prime Minister Navin Ramgoolam aiming to assume control when the US lease was set to expire in 2016. However, the lease was renewed until 2036, citing defence and security interests, as well as the feasibility of ceding control. Port Louis continued to campaign for Chagos’ return, involving the International Court of Justice, resulting in a non-binding advisory opinion in February 2019 that determined the UK had wrongfully displaced the Chagossian population and should return control of Chagos. Despite the ICJ opinion and UN Resolution 73/295 in May 2019, that requested the UK give up control within 6 months, the British government continued to flout Chagos’ return to Mauritius.
Disputes over Chagos’ control remained relatively absent from international discussions from 2019. However, following the Labour Party’s election victory in July 2024, Port Louis and London reached an October 2024 agreement that would restore the Chagos Archipelago to Mauritian governance, whilst leasing Diego Garcia for 99 years. Though it appeared a long-awaited breakthrough had been achieved, Ramgoolam’s return to the Mauritian premiership stalled negotiations. Chagos’ negotiations by the previous administration were confidential, and an independent review by Ramgoolam’s government led to a series of counter proposals that sought terms more favourable to Mauritius. Alongside other concerns, Port Louis’ primary grievance was the governance of Diego Garcia under British-American interests. Whilst previous terms secured the military site for annual payments of $90 million, Mauritian proposals sought front-loaded payments adjusted for inflation. Moreover, whilst the Biden administration welcomed the return of the Chagos Archipelago to Mauritius, the return of Trump to the White House, operating a far more hawkish policy towards China, has uprooted the potential for a deal on previously-negotiated terms, and reaffirmed the importance of Diego Garcia as an asset in the US’ strategic arsenal.
Why Did the UK Agree to Return Chagos?
What changed the UK’s position on Chagos? The party line of previous conservative administrations underlined the military importance of Diego Garcia, and feared the security concerns posed by Mauritian control of the wider archipelago as it continued to deepen ties with China. Following a return to Downing Street in July 2024, Labour policy on Chagos appears defined by international law and growing opprobrium on the diplomatic scene. Whilst it has looked to protect control of Diego Garcia for at least a century, London committed to return the islands to safeguard global security, limit illegal immigration and protect its relationship with Mauritius . Global criticism condemned a growing trend of great powers only respecting a rules-based international order if and when it suited them. Returning sovereignty to Mauritius aims to quell these critiques.
However, if the UK cared so much about its international reputation, why has it paused negotiations to wait for a Trump verdict on the deal? Relations so far between the UK and US leaders have been mixed. After Trump secured his re-election in 2024, 2018 comments from the British Foreign Secretary were uncovered labelling the President-elect a neo-Nazi sociopathic tyrant (Mason and Morton, 2024). In January 2025, Trump’s close ally Elon Musk heavily criticised UK PM Keir Starmer in his handling of the UK grooming scandal, though the US leader clarified his ‘very good relationship’ with his British counterpart UK hesitations awaiting US considerations might come as the UK looks to protect its ‘Special Relationship’ with an increasingly-isolationist US.
Why Might President Trump Look for New Conditions on the Deal?
A new president means fresh scrutiny for the Chagos deal. Whilst the Biden administration supported the return of Mauritian sovereignty over the islands in accordance with international law, the foreign policy objectives of the Trump administration might jeopardise the conditions of the current Chagos agreement. President Trump is a man committed to the ‘Art of the Deal’, and is highly unlikely to commit to any treaty that damages American interests. US Secretary of State Marco Rubio has argued that ceding control of the Chagos archipelago to Mauritius poses a ‘serious threat’ to the United States as Mauritius continues to shore up ties with China.
In 2019, Mauritius became the first African country to sign a free-trade agreement with China. Huawei has escalated investments in the African island nation in recent years, becoming involved in training, energy and coral reef protection programmes.
Ceding complete control of Chagos to Mauritius risks Diego Garcia two-fold. In the short-term, it exposes the military site to security concerns should Sino-Mauritian ties deepen. As of yet, the Chagos Marine Protected Area has limited external maritime presence around Diego Garcia. Returning the islands might open the zone to Chinese vessels, even with a lease on Diego Garcia. In the long-term, the current conditions of the deal seek to remove the unilateral ability of the UK to extend the lease a further 40 years. The military base is strategically invaluable. The US continues to clash with Houthis in the Red Sea, intends to remain intimately involved in the Gaza situation, and needs regional presence to counter China’s inevitable increase in territorial aggression in the South China Sea. Without the ability to secure Diego Garcia’s future, American foreign policy abilities remain uncertain.
So, What’s Next?
Donald Trump has yet to decide the fate of the Chagos deal. As is all so often the case in great power-small nation disputes, the deciding verdict will come from the dominant side, with the UK and US controlling the outcome.. Mauritius remains committed to Chagos’ return to culminate its decades-long campaign for independence and complete decolonisation, but the threat of growing ties with China will determine whether it achieves territorial consolidation. International reputation influenced the UK to concede sovereignty over the archipelago, but President Trump has time and time again shown his absolute indifference to how the US is viewed on the international scene. Whilst his views on China are ambiguous, he has staffed the White House with more hawkish policy advisors, and his commitment to sweeping tariffs suggests he’s leaning this way too. Eventual Mauritian sovereignty over the Chagos archipelago is highly likely, but only if American (and British) strategic interests can be protected in the long term.
Bibliography
Anelay, Baroness of St. Johns. (2016). Update on the British Indian Ocean Territory. UK Parliament. [online] 16 Nov. Available at: https://questions-statements.parliament.uk/written-statements/detail/2016-11-16/HLWS257
Bengali, S. (2018). A half-century after being uprooted for a remote U.S. naval base, these islanders are still fighting to return. Los Angeles Times. [online] 14 Aug. Available at: https://www.latimes.com/world/africa/la-fg-britain-us-diego-garcia-20180814-story.html
Cater, L. (2025). Starmer doing ‘very good job,’ Trump says after Musk’s attack on UK leader. Politico. [online] 26 Jan. Available at: https://www.politico.eu/article/donald-trump-keir-starmer-doing-very-good-job-elon-musk/.
Eighth National Assembly. (2025). Parliamentary Debates (Hansard) (Unrevised). Republic of Mauritius. [online] 4 Feb. Available at: https://mauritiusassembly.govmu.org/mauritiusassembly/wp-admin/admin-ajax.php?juwpfisadmin=false&action=wpfd&task=file.download&wpfd_category_id=472&wpfd_file_id=21893&token=&preview=1
Gregory, F. (2025). The U.S. Shouldn’t Have to Stop Britain’s Disastrous Chagos Deal. National Interest. [online] 5 Feb. Available at: https://nationalinterest.org/feature/us-should-stop-britain-disastrous-chagos-deal
Lawal, S. (2024). Why is the UK handing the Chagos Islands back to Mauritius? Al-Jazeera. [online] 4 Oct. Available at: https://www.aljazeera.com/news/2024/10/4/why-is-the-uk-handing-the-chagos-islands-back-to-mauritius
Mason, C. and Morton, B. (2024). Lammy dismisses past criticism of Trump as ‘old news’. BBC News. [online] 7 Nov. Available at: https://www.bbc.co.uk/news/articles/cm2z1zm1pk3o
Mercer, D., Cuddy, A., and Landale, J. (2025). UK’s Chagos deal on hold to allow Trump review. BBC News. [online] 15 Jan. Available at: https://www.bbc.co.uk/news/articles/cwyp3750y3po
O’Shaughnessy, K. (2024). The UK deal on Diego Garcia is positive, but it won’t reverse declining support for rules-based order. theinterpreter. [online] 8 Oct. Available at: https://www.lowyinstitute.org/the-interpreter/uk-deal-diego-garcia-positive-it-won-t-reverse-declining-support-rules-based-order
Penna, D. (2024). Starmer hands Chagos Islands back to Mauritius. Telegraph. [online] 3 Oct. Available at: https://www.telegraph.co.uk/news/2024/10/03/starmer-chagos-islands-sovereignty/
UK Government. (2024). UK and Mauritius joint statement, 3 October 2024. gov.uk. [online] 3 Oct. Available at: https://www.gov.uk/government/news/joint-statement-between-uk-and-mauritius-3-october-2024
