Chagos – Strategic realignment or sovereignty surrender?

The agreement between the UK and Mauritius came when the UK and the United States found increased utility for the British Indian Ocean Territory.

With the rise of Asian powers, mainly China, the military facilities on the island of Diego Garcia are central to Anglo-American power projection and relative control of the Indian Ocean.

A transfer of sovereignty might weaken the UK’s strategic position, while soft power gains within the so-called “Global South” will be ephemeral and result in scarce practical gains for London. Lastly, Chagossians might still face challenges in returning to their homeland.

This article is the opinion of the author and not necessarily that of the UK Defence Journal. If you would like to submit your own article on this topic or any other, please see our submission guidelines. 

On 3 October 2024, less than three months after Labour won the July general election and became the governing party in the UK, the new British government, under the leadership of Prime Minister Sir Kier Starmer, announced an agreement with the Republic of Mauritius that will end UK sovereignty over the British Indian Ocean Territory (BIOT), forming the Chagos Archipelago, in exchange for a British-managed 99-year-lease over the island of Diego Garcia. London stated that a treaty in the following months would formalise the agreement in principle with Mauritius.

Negotiations officially started under the Conservatives under Rishi Sunak (2022-2024) in November 2022, displaying a break from the long-standing position of the UK on the issue. In early 2024, Lord Cameron, then Foreign Secretary, signalled that the British government had clear reservations on sovereignty and the return of displaced Chagossians to the territory. The Labour victory in July led to the reopening of sensitive points of the negotiation, which resulted in the October announcement, the first transfer of a British overseas territory since Hong Kong in 1997.

Historical Background and Strategic Importance

Before advancing into what has been agreed upon between the UK and Mauritius and the consequences to British foreign and defence policy, an overview of the history and utility of the BIOT, particularly the island of Diego Garcia, is necessary. The British Indian Ocean Territory is formed by the Chagos Archipelago, which comprises over 50 islands with a total land area of roughly 56. 1 km² or 21. 6 square miles. Diego Garcia is the territory’s largest and most relevant island, accounting for more than half of the territory’s land area with 60 km² or 12 square miles, and has been the only permanently inhabited since the first plantations were opened under French initiative in the 1770s. The relevance of Diego Garcia’s geostrategic location in the “centre” of the Indian Ocean, south of the Indian subcontinent and halfway between Africa and Southeast Asia, enabled an otherwise tiny island to play a significant role in British defence and security policies in the Indian Ocean and beyond.

European presence commenced with the chartering of the archipelago by Portuguese explorer Vasco da Gama in the early sixteenth century. France was the first power to lay claim over the islands as part of its colony of Isle de France (including the island now known as Mauritius). The country was also the first to assess the strategic value of Diego Garcia, the main island of the Archipelago. A 1768 French survey report led the government in Paris to appreciate the strategic position of the island. In the following year, France surveyed Diego Garcia, concluding that the island had a spacious bay safe for anchorage. The French government encouraged settlement. In the late 1780s and 1790s, coconut plantations were the main reason for settlement, with the plantation owners sending slaves and contractors to the Chagos Archipelago, mainly to Diego Garcia, creating the first settlements on the islands. In 1786, the East India Company attempted to settle on Diego Garcia, forcing several French settlers to leave. When the Company left, the French briefly used the island as a leper colony. By 1793, the coconut plantations were already the main economic force of Diego Garcia.

In 1814, the territory was transferred to Britain after decades as part of France’s colonial empire. Four years earlier, during the height of the Napoleonic Wars, the British had captured the colony of Isle de France. The Treaty of Paris of 1814 formally transferred the Isle to the British, including the Seychelles, Rodrigues, Tomelin Island, Agaléga, Cargados Carajos Shoals, and the Chagos Archipelago. Throughout the nineteenth century, the British locally administered these new territories from the then-renamed “Mauritius”. The Seychelles were separated by Britain from the crown colony of Mauritius in 1903. Throughout the Victorian Era (1837-1901), the plantations remained the main economic activity of the Archipelago. Coconut oil was produced to supply the demands of the colony of Mauritius. In the early 1860s, only Diego Garcia produced half of the consumption of Mauritius. In 1881, Diego Garcia became the base for two coaling stations to support the global operations and primacy of the Royal Navy and private navigation companies. According to the Methuen & Co. publications, those stations remained downgraded as “coaling ports” until the mid-1900s. The 1880s also witnessed the “Oilmaking Company of Diego and Peros”, backed financially by French financiers and Mauritian-based investors, taking control of all the coconut plantations of the Archipelago. The Company would effectively control much of the local population’s life and work conditions until the 1960s.

With one exception, the First World War passed without major incidents for the small number of inhabitants of the Chagos Archipelago. In the first weeks of the conflict, communication delays between Diego Garcia, British Mauritius and Britain led to the small naval facility of the island receiving the German light cruiser SMS Emden after the vessel had performed raids throughout the region, unaware of the state of war. The small British garrison based on the island treated the Germans to a warm reception. Following a short stay, the light cruiser left the territory to resume attacks against vessels of the Entente. The Emden faced her final battle a few weeks later when she was disabled by the Australian cruiser HMAS Sydney and grounded off the Cocos Islands on 9 November 1914.

During the Second World War, Diego Garcia received increased attention from London. In 1942, Britain opened a Royal Air Force station on the island, known as RAF Station Diego Garcia. Additionally, an advanced flying boat unit of No. 205 and No. 240 Squadrons based in Ceylon was established at East Point Plantation. The primary purpose of these forces included the search for Axis surface raiders and submarines. This task used several British flying boat patrol bombers, “Sunderland”, and the American flying boat and amphibious aircraft “, Catalina”. The British government also reinforced Diego Garcia’s defence by deploying a Royal Marines detachment and installing two 6-inch naval artillery pieces. In April 1946, shortly after the end of the war, the RAF station was closed.

In the first two decades of the Cold War, the decolonisation process of the British Empire moved forward in Asia with the independence of British India in 1947, followed by Burma and Ceylon in 1948, leading to reassessments in London on the British engagement with the region. In the late 1950s and 1960s, the “winds of change” hit the African continent, with all British continental possessions achieving de facto or de jure independence by 1966. Hence, the chief motive justifying an extensive British presence in the region was gone, and the gradual loss of colonies equally led to a deprivation of military bases. Therefore, although the UK sought to downgrade its military profile East of Suez in the 1950s and early 1960s, the British government also wanted to remain a strategic actor directly attached to the region while attempting to find a new role in the Cold War era. The BIOT would find its origins within this context of change in Britain’s place in the international system.

Cold War Developments and the Creation of BIOT

The early 1960s service rivalry between the Royal Navy and Royal Air Force would define the future of the Chagos Archipelago. While the Government in London reviewed the strategic imperatives of the coming decades, the debate quickly became dominated by power projection. In other words, the heads of the Royal Navy and RAF scrambled to convince the Government how the UK could best project power globally. The National Archives in London have preserved the extensive and numerous amounts of minutes, meetings, exchanges and reports from those involved in the debate between 1960 and 1964. In short, on the one hand, the Navy supported replacing the ageing fleet of aircraft carriers – HMS Victorious, HMS Ark Royal, HMS Hermes, and HMS Eagle – with a new project of up to four carriers. The project was known simply as CVA-01, referring to the first ship of the class. On the other hand, with support from the Treasury, the RAF proposed an ‘Island Bases Strategy’ or ‘Ocean Island Policy’ with airpower projected from overseas territories around the globe.

The then Air Ministry argued that air power was far less costly than the Navy’s carrier programme. With that aim, several locations were selected for a possible Island Strategy, including Gibraltar, Ascension, Gan, and Aldabra; The latter would be part of the BIOT until 1976. The counterargument of the Admiralty covered the issue of the uncertainty over the future British sovereignty rights over these territories and the flexibility of the carriers. Indecision in London led to the approval of the Royal Navy aircraft carrier fleet in July 1963. Nevertheless, the debate persisted well into 1964 and 1965, with the British government changing its previous decision and opting for the plans of the RAF. By the time the CVA-01 programme was cancelled in January 1966, the British were already moving to secure a foothold in the Indian Ocean and in talks with the the United States.

While the UK wanted a system of bases to support its global reach by air power, the the United States had expressed interest in a possible territory with no local inhabitants to use as a military base in the Indian Ocean. In February 1964, the British and Americans initiated secret negotiations on using Diego Garcia or Aldabra as a future base for the the United States. In November 1965, the UK officially created the British Indian Ocean Territory, detaching the Chagos Archipelago from the colony of Mauritius and the islands of Aldabra, Farquhar and Desroches from another British colony, the Seychelles. The British government paid a sum of £3 million to the self-governing colony of Mauritius as compensation. This was aimed at constructing an Anglo-American military base on Diego Garcia. Concomitantly aligned with the Island Strategy, the British also planned to establish an RAF base in Aldabra with an open possibility of American participation. However, the scheme faced opposition in Britain, generating the ‘Aldabra Affair’. By 1966, the British had decided to operate on RAF Gan – north of Diego Garcia – instead of pushing the case of Aldabra.

However, the growing economic pressure on the Government due to the problems of the British economy led to the 1967-1968 British announcement of the strategic withdrawal from East of Suez. London abandoned plans for the additional base on Aldabra or neighbouring islands. Still, discussions on a fleet of light carriers – or officially ‘through-deck cruisers’ – emerged in the late 1960s, resulting in the Invincible class, built between 1973 and 1981. By 1976, when the RAF Gan closed, and the facilities were handed to the Maldives, the British position in the region had already changed considerably. In that same year, Britain transferred the islands that were once part of the Colony of Seychelles to the newly independent nation of the Seychelles. The Island Strategy had displayed a fault that the Admiralty had highlighted in 1963 as the availability of British territories dwindled rapidly, leaving the UK with only the BIOT by the early 1980s. The result was that the UK found itself in the 1980s with a hybrid position between what the by-then-defunct Air Ministry and Admiralty wished for twenty years earlier. The Royal Navy operated a fleet of light aircraft carriers and had access to the Anglo-American base in Diego Garcia, a secondary remnant of the Island Strategy.

Although created by the UK in November 1965 for a possible Island Strategy and American presence, the BIOT would only be formally selected to be home of a base for the the United States on 30 December 1966 when the two countries executed an Exchange of Notes. Initially, Britain allowed the the United States to use the BIOT for defence purposes for 50 years – until December 2016 – followed by an extension of 20 years as long as neither side declared its intention to terminate the agreement within two years before its renewal. Britain has the right to determine additional terms when the deal is renewed. In exchange, the the United States made no direct monetary payment to Britain. Instead, the British received a discount from the Americans on acquiring the submarine-launched ballistic missile system (SLBM), the Polaris missiles.

From the perspective of the the United States, the island of Diego Garcia was the ideal place to set up a military base. Politically, its closest ally was administrator and sovereign and no other power held claims or interests over the land. Geographically, Diego Garcia was distant from latent threats while strategically located at the heart of the Indian Ocean. Controversially, the small population of the Chagos Archipelago also reinforced the view of its ideal position, settling the future of its population. Chagos’ inhabitants were mainly contract workers of Indian, Malay, and African ancestry, known as Chagossians; most lived on Diego Garcia and worked on the plantations for generations. Following arrangements between the the United States and Britain, the native population of roughly 1, 000 Chagossians had to be removed from the main island to allow the construction of the military facilities. Initially, the British adopted “indirect methods” to influence the inhabitants to leave “willingly”, including restricting medical supplies and food or prohibiting those who left the island from returning. When the American construction teams arrived in 1971, the efforts doubled with the closure of the last plantations. Between 1971 and 1973, the remaining Chagossians were forcibly removed to Mauritius after Britain paid the recently independent nation a sum to resettle the last islanders.

A relatively small Naval Communications Station (NAVCOMMSTA) was completed in 1973. Three years later, in 1976, Britain and the the United States signed an agreement that allowed “to develop the present limited naval communication facility on Diego Garcia as a support facility of the United States Navy”. When completed, the “support facility” included enlargement of the airfield, increased personnel accommodation, an anchorage and transmitting and receiving services. This infrastructure aimed to provide an enhanced stagging and furnishing point for American and British vessels and aircraft. Improving the military facilities was seen in Washington as part of its reaction to counter a series of geopolitical setbacks in the region that had been occurring since 1970. Playing a central role in the the United States’ calculations included the closure of the listening posts of Peshawar Air Station in Pakistan and Kagnew Station in Eritrea, the ascension of the Khmer Rouge in Cambodia – with the Fall of Saigon and the Mayaguez incident –, the growing Soviet naval presence in Aden and Soviet involvement in expanding an airbase (the Baledogle Airfield) in Somalia.

However, the geopolitical winds would continue to blow against the Anglo-American interests in the regions East of Suez. Following the 1979 Iranian Revolution, which led to the fall of the Shah of Iran and the creation of a hostile regime confirmed by the Iran Hostage Crisis (1979-1981), the the United States and Britain reviewed their position in the Persian Gulf and Indian Ocean. London and Washington became increasingly concerned with the security of the sea lane crossing the Persian Gulf and the Strait of Hormuz, through which significant amounts of oil destined for Western markets flew every year. As part of the American reaction to the changing geostrategic balance of the region, the the United States engaged in new negotiations with Britain to receive permission to expand the military facilities on Diego Garcia. Following the British approval, the Americans initiated the build-up of infrastructure that, by the end of the decade, included two 3, 700 m (12, 000 foot-long) runways, expanded parking aprons, a deep-water pier, 20 new anchorages, maintenance buildings, living quarters for military and civilians, aircraft hangars, fuel storage and new port facilities for the largest American and British vessels. In 1985, the expanded port facilities were completed, and the Forrestal-class aircraft carrier USS Saratoga was the first of its kind to use the new port. By the end of the 1980s, Diego Garcia had been transformed into one of the leading overseas military bases of the the United States and the main base available to Britain in the area.

In the 1980s, despite apparently agreeing with the 1965 separation, Mauritius laid claim over the islands, citing the British actions before the country’s independence to establish the territory as illegal. Britain has repeatedly rejected Mauritius’ claims for most of the BIOT’s history. However, the British declared they intended to cede the Archipelago to the African nation “when it is no longer required for defence purposes”. Debating in 2008, a of the House of Common indicated that a prevailing view of Mauritian governments is that they were regarded as inferior, a “non-independent country”, and that back in 1965 Mauritius was concerned about negotiating its independence terms and “it had its arm twisted, it was in a lower bargaining position and it was not true consent when it agreed, in return for £3 million, to cede the islands to Britain”. At the time, the Select Committee asked the leader of the Chagos Refugees Group, Mr Bancoult, whether a possible resettled Chagossian community would choose to be British under the BIOT or part of Mauritius. Mr Bancoult replied that if presented with that choice, he believed they would prefer to remain British. Notably, the Committee concluded that any decision on the sovereignty dispute over the BIOT must consider the Chagossians’ wishes. A position that would be ignored between 2022 and 2024, resulting in a row of uncertainty over the future of the Territory.

In the 1990s and 2000s, Diego Garcia remained a relevant military base, particularly as the the United States engaged in military operations in Iraq and Afghanistan. Considered by British and American officials as not covered by the African Nuclear-Weapon-Free Zone Treaty – also known as the Pelindaba Treaty – Diego Garcia was home to nuclear-armed Boeing B-52 Stratofortress strategic bombers during the Gulf War. The military facilities also supported the deployment of allied troops and assets to operations in Afghanistan and Iraq, with Australian and Japanese forces using the island. The island of Diego Garcia is also home to one of four dedicated ground antennas that assist in the operation of the well-known Global Positioning System (GPS), with the other antennas located on Cape Canaveral, Kwajalein, and the British island of Ascension.

In 2000, after a British Court declared unlawful the ordinance that authorised the forcible removal of the Chagos inhabitants in 1971 from their homeland, the UK agreed to allow the return of Chagossians to all islands of the Archipelago except for Diego Garcia due to security reservations. The Government in London moved to revoke laws that prevented the resettlement. It is worth noting that in 2002, amidst increased military activity on the BIOT, the British government offered citizenship to some Chagossians. Many came to live in Britain, joining the small but long-established British-Chagossian community. However, in 2004, the decision to allow Chagossian back to the outer islands was followed by a U-turn from Britain, returning to its position of banning any resettlement. This decision might have occurred partly due to the ongoing “War on Terror” and the crescent investments and centrality of the territory to the the United States and Britain to a lesser extent. Legal battles would continue in the following years. In 2010, the British government created a BIOT Marine Protected Area, which was received with mistrust by Chagossians because the move could prevent any future resettlement due to the impossibility of fishing as a source of food and income for the local population. Notably, Britain permitted an exemption to fishing to supply personnel from the Anglo-American base.

The continued strategic importance of the territory has blocked the debate over a possible resettlement of the Chagossians. Strategically, Diego Garcia is seen as one of the Anglo-American “unsinkable aircraft carriers”, an island that expands its reach and reduces the costs of military power projection into several regions. In the case of Diego Garcia, the areas that can be influenced include the Middle East, South and South-East Asia, Australia and East Africa. Concomitantly, the American officers have already regarded the island as the “Malta of the Indian Ocean”, contributing to the reasoning behind the persistent military presence and interest in the territory and its central position as one of the most relevant overseas military bases of the the United States and Britain.

In the 2020s, the the United States maintained its policy of Diego Garcia as a key military complex for its regional deployments and operations. The military infrastructure and personnel based on the islands are organised under the auspices of the “Naval Support Facility Diego Garcia”, with the name “Camp Thunder Cove” being used as a synonym for the whole presence, although encompassing only a sector of the base. Britain labels the base as a “Permanent Joint Operating Base (PBJOB) Diego Garcia”, and British personnel operate within the bureaucracy of the “British Forces British Indian Ocean Territory” (BFBIOT). Britain retains access to the facilities, remaining responsible for the administration of the territory, with the BFBIOT permanently having roughly 40 to 50 British military personnel responsible for carrying out administrative duties of the British Indian Ocean Territory. Most British forces stationed on Diego Garcia are part of the Naval Party 1002.

Britain also maintains a vessel for fishery and military patrol duties. Since 2010, when the marine reserve was created, patrolling the fisheries of the BIOT has resulted in an increased number of apprehensions of illegal vessels. In late 2016, the British administration of the Territory signed a contract with North Star Shipping – based in Aberdeen, Scotland – to replace the ageing MV Pacific Merlin, built in 1978 and deployed to Diego Garcia for at least a decade. Built as a “standby-safety vessel”, the MV Pacific Marlin displaced a gross tonnage of 1200 tonnes, being 53 metres long with a breadth of 12 metres and was removed from her services to the BIOT in early 2017 when the MV Grampian Frontier entered service. The Grampian Frontier was built in 1997 as an “Offshore Supply Vessel” at 68 metres long with 14 metres of breadth and a gross tonnage displacement of 2064 tonnes. The BIOT Administration regards the ship as “more capable than its predecessor, in addition to which, we employ a range of specialist capabilities to enhance the surveillance and enforcement effort”. The “patrol vessel” operates in conjunction with the Naval Party 1002 for security and defence matters, also having a role in maritime research and conservation. It is worth mentioning that, in 2022, Grampian Frontier shadowed a Mauritian-charted vessel – sponsored by the Government of Mauritius and with Mauritian officials onboard – that brought some Chagossian to the Blenheim Reef within the BIOT. Since the UK permanently deployed two Offshore Patrol Vessels (HMS Tamar and HMS Spey) to the Indo-Pacific in late 2021, Diego Garcia was visited by HMS Tamar in 2023 for patrol duties.

On average, the American presence is roughly 2, 500 military personnel. However, due to the extensive usage of the facilities by the the United States, the numbers fluctuate beyond 5, 000 military personnel with ease. When considering civilian contract workers, these numbers might be more expressive. In the late 2010s and 2020s, the the United States had assets of the US Navy, US Air Force and Space Force on the island. The US Navy has at its disposal most of the Navy Support Facility. Also, it maintains a site for the “Diego Garcia Detachment” of the Naval Computer and Telecommunications Station (NCTS) Far East. Moreover, the Navy’s Military Sealift Command permanently deploys a Maritime Pre-positioning Ship Squadron to the Anglo-American base. The Navy also maintains a supply centre for the fleet’s industrial and naval demands and assets. At the same time, the Air Force bases detachments of the Pacific Air Forces (PACAF) and Air Mobility Command. Lastly, the detachments of the 20th Space Control Squadron and 21st Space Operations Squadron of the US Space Force also operate from Diego Garcia. Demonstrating the continued relevance of Diego Garcia, in 2025, the the United States deployed additional Northrop B-2 Spirit bombers, for operations in the Middle East.

Sovereignty Disputes and International Legal Challenges

However, by the 2010s, the status of the British Indian Ocean Territory began to be questioned within the frameworks of international organisations. In 2017, the United Nations General Assembly voted to refer the issue to the International Court of Justice (ICJ). The voting occurred in a context that displayed the rift between the UK and its European allies following Brexit. Even though the British remained committed to the security and defence of Europe through NATO, continued to be a relevant partner, cooperated in several fields internationally and shared a similar world view of protecting the rules-based international order, Canada and most European nations abstained. Only 15 countries voted against the resolution and supported the UK. The complete list included Afghanistan (then governed by a Western-backed administration), Albania, Australia, Bulgaria, Croatia, Hungary, Israel, Japan, Lithuania, Maldives, Montenegro, New Zealand, the Republic of Korea, the the United States and the UK. Meanwhile, 94 countries voted in favour – including all of Africa – and 65 abstained. The British government warned the General Assembly about the risk of weakening the legitimacy of the Court and that Britain “did not and would not consent to the bilateral dispute being submitted for judicial settlement”.

In February 2019, the ICJ issued an advisory opinion that concluded that “the United Kingdom is under an obligation to bring to an end its administration of the Chagos Archipelago as rapidly as possible”. A few months later, in May 2019, stating that “Chagos Archipelago forms an integral part of the territory of Mauritius” and should be returned within six months. The resolution was approved by 116 votes to 6. The countries voting against it were the UK, the the United States, Israel, Australia, Hungary and the Maldives. Except for the Maldives, which had an interest in the BIOT, the remaining countries expressed their surprise at the language used by the ICJ and the Assembly. The American delegate stated that all should be concerned about the “overreach” of the resolution and reminded those present that “the draft resolution would undermine the international legal principle that States must consent to have their disputes adjudicated”, a reference to the UK’s opposition, to refer the case to the ICJ. Australia also expressed “deep concern” that the General Assembly is being asked to implement a non-binding opinion.

The British delegate, Dame Karen Pierce, stated: “The United Kingdom is not in doubt about our sovereignty over the British Indian Ocean Territory”. The British delegate pointed out the issue raised by other partners that the Court has allowed its principle of not hearing bilateral disputes without the consent of both parties to be bypassed, allowing any future bilateral dispute to become the target of an opinion. Citing the resolution, the delegate stressed that the text goes beyond the ICJ’s advisory opinion, particularly by setting a six-month deadline for the UK to act and inciting States to take actions that could undermine regional security. Dame Karen Pierce also declared that “the Court does not give sufficient regard to material and factual issues” highlighted in her letters “, nor does it consider the 2015 International Tribunal for the Law of the Sea arbitration award holding that the agreement — in which Mauritius agreed to the detachment in return for access to and resource benefits — is legally binding”.

The first consequences of the resolution could be seen in the statement of Argentina’s delegate, which raised the “dispute” over the Falkland Islands, South Georgia and the South Sandwich Islands. Argentina declared that the Assembly recognised the primacy of “colonial issues”, arguing that the principle of self-determination was not applicable in those cases. Britain rebuked the Argentinian declarations and reaffirmed the right of self-determination of its Overseas Territories and their right to remain British if so desired by their inhabitants. However, the precedent was set by both the ICJ and the UN General Assembly. Six months later, Britain ignored the Assembly’s resolution and the Court’s advisory opinion by simply continuing to hold sovereignty over the British Indian Ocean Territory and refusing to negotiate the future of the territory with Mauritius. As Britain and the the United States warned, the decision of the Court to hear the case and the General Assembly to vote for a resolution that carried a language not used by the Court – including the demand to return the BIOT to Mauritius within six months – only raised legitimacy questions and demonstrated that in great power politics, the Assembly and the ICJ had little effective power.

In 2021, in an apparent U-turn on its 2015 ruling, the International Tribunal for the Law of the Sea ruled that the UK had no sovereignty over the Chagos Archipelago. The ruling came as part of a dispute between Mauritius and Maldives over maritime boundary delimitation and did not include the UK as one of the hearing parties. In the following year, a chartered vessel with Chagossians and officials of the Mauritian Government, including the Permanent Representative of Mauritius to the United Nations, visited the outer atoll of Peros Banhos and surveyed the Blenheim Reef without British authorisation but shadowed by the Grampian Frontier, the locally-based British patrol vessel.

The 2024 Agreement and Future Implications

Following the Russian invasion of Ukraine in February 2022, some analysts saw the issue of the Chagos Archipelago as an obstacle for Britain to convince “developing” countries to adopt economic and diplomatic measures in line with the West against Russia. During her short-lived premiership, Liz Truss met with her counterpart from Mauritius. The perception that the BIOT hindered British influence might have grown in the months after the Russian invasion of Ukraine, with regional players attempting to balance between China-Russia and the West. Within months, in November 2022, the British government announced that the UK and Mauritius had commenced negotiations on the sovereignty of the BIOT with the continued operation of the Anglo-American base on Diego Garcia as a prerequisite. In December 2023, the British terminated these negotiations after the agreement negotiated by the Foreign Office did not achieve the aims of the Sunak Government (2022-2024). The gains were deemed insufficient to relinquish British sovereignty. Nevertheless, the change of government in July 2024, with the Labour Party under the leadership of Sir Kier Starmer, abruptly led to renewed negotiations and the announcement on 3rd October 2024 that the UK and Mauritius had reached an agreement that included the UK relinquishing sovereignty of the Chagos to Mauritius, with support from the the United States.

Renegotiated in only three months, the October 2024 Agreement between the two countries covered the base’s future, the possible settlement in the outer islands and the British role in the new arrangement. However, detailed information disclosed in the following months remained scarce. Preliminary information on the agreement indicated that it could raise the costs of operating the base as the UK had committed to providing a “package of financial support” to Mauritius, which would occur as annual payments and investments. For example, the, without personnel costs, were £157. 92 million in the 2018-19 Fiscal Year, £169. 43 million in 2019-20 and £171. 71 in 2020-21.

By comparison, in the same timeframe, the annual cost of running the British Indian Ocean Territory was £3. 4 million, behind the facilities in Oman (£3. 5 million), Bahrain (£4. 2m), United Arab Emirates (£7. 7m), Kenya (£9. 3m), Canada (£27. 9m), and the Sovereign Base Areas in Cyprus (£80m). The actual costs remained undisclosed as the Labour Party completed seven months in government. However, press reports – rebuked by both the UK and Mauritius – indicated that the total value could be billions of pounds. Moreover, with the agreement, Mauritius could begin a resettlement programme on the outer islands, with Diego Garcia remaining off-limits. The base would stay on lease for “an initial period” of 99 years for the UK, and the British would be responsible for its administration. In May 2025, the British government confirmed that the deal with Mauritius would cost the UK an additional £101m a year.

Nevertheless, the agreement’s implementation faced two significant setbacks within weeks of its announcement. In early November 2024, with Donald Trump winning the US presidential election and members of Trump’s team having declared their opposition to the deal with Mauritius, citing the influence of China over the latter, the viability of the agreement was put in question. Days later, Mauritius witnessed the election of a new Prime Minister, who also expressed reservations about the agreement over the Chagos Archipelago. Meanwhile, the negotiation ignored the position of the Chagossians. Britain, in particular, did not seek to include Chagossians and survey their position, which has already shown to be more favourable to Britain than Mauritius would like.

Instead, London let the discourse of decolonisation, the opinion of multilateral institutions that overstepped their scope, and the detachment of the Chagos Archipelago from the Crown Colony of Mauritius in 1965 dictate the conversation. For the Chagossians, their main issue is not being under British sovereignty but being allowed to return to the archipelago. Thus, the islanders did not speak with consensus over the future of their homeland. The community is divided. Some desire to return to live on the islands, while others worry about their rights and status as British citizens. Some oppose the agreement, stating that Chagossians are different from Mauritians. Chagossian Voices, a community organisation for those based in the UK and other countries, declared its dismay at the exclusion of the Chagossians from the negotiations. In short, the position recommended in 2008 by a Parliament Select Committee that successive British governments should consider the will of the islanders as a starting point for the debate on sovereignty was ignored leading to the 2024 Agreement displeasing several sectors of the Chagos community while possibly rising operational costs and terminating British sovereignty over its last foothold in the Indian Ocean. The apparent distancing of the Trump Administration from the question in the early 2025 also seems to embolden the British government to go for the deal with Mauritius. Within this context, a last-minute attempt in May 2025 that led to the agreement being blocked by London’s High Court failed to prevent the mistake receiving the backing of the Labour Government.

The mismanagement of the Chagos question exposes Britain as plagued by insecurity, unable to manage questionable moralism and non-binding decisions from international organisations. The deal also shows the misplaced expectation of the UK that the action would gather favour or sympathy from the so-called “Global South” by enhancing British and Western soft power in the Indo-Pacific while strengthening the rules-based world order. Within this context, the British government framed the agreement as part of de-escalating the pressure on Britain to uphold the rules-based order as a direct counterbalance to growing Chinese influence.

Despite that, accusations of hypocrisy against Britain from other countries of the periphery or semi-periphery will not cease with the end of British sovereignty over the Chagos Archipelago. On the contrary, the case of Chagos has been seen by Argentina as a possible solution to obtain sovereignty over the Falkland Islands while instigating doubt about the future of other territories, including Gibraltar. The whole premise behind the British dealings with Mauritius ignores the deep-seated discontent across most non-Western countries with the current world order. No number of concessions by Britain could revert that sentiment. Additionally, Mauritius’s apparent gains have shown that multilateral institutions can provide victories to small actors against insecure major powers.

However, all major powers are aware that these institutions are in place to preserve the status quo, meaning creating the bases to ensure the continued dominance of the current hegemon – the the United States – and its main allies. As seen before, when the Great Powers no longer see the current order as beneficial to their interests, these powerful players are the first to move to make a new order. China, among many other things, sought more relevance in multilateral institutions and became an enthusiast of BRICS. At the same time, Russia was obsessed with remaining a Great Power by reinforcing its influence in its neighbourhood. With the second term of Donald Trump, the the United States seems to have a new vision for the world order, which is not necessarily shared across the Atlantic. Britain’s dealings with Mauritius might show that the country is rightfully worried about the future of the current world order but is applying the wrong remedy in an attempt to maintain the status quo.

As the world moves away from a brief period that witnessed sparse or no competition among the Great Powers and delves into a new age of realism and Great Power politics, the UK might be relinquishing its last foothold in the Indian Ocean for almost no return. This is particularly true when considering that the British and Americans have agreed to resettle the outer islands of the BIOT, which could have seen a renewed local Chagossian community under British sovereignty if the UK had not played into discourse propagated by Mauritius. However, the British government started to believe in the illusion that the UK would be marginalised in international forums and the future of the base would be uncertain, clearly underplaying the weight of the UK in the international system and proving that declinism and its distortion of reality is far from leaving British politics.