The Chagos Archipelago in the middle of the Indian Ocean comprises Diego Garcia and more than sixty other islands. The Archipelago has been under continuous UK sovereignty since 1814 and was for most of that time administered as part of “British Mauritius.” In 1965, three years before the UK granted independence to Mauritius, it detached the Chagos Archipelago from British Mauritius and began to administer it separately as the “British Indian Ocean Territory” (the BIOT). Together with the attendant Exclusive Economic Zone waters, the BIOT comprises 21,000 square miles of strategically vital territory that hosts a major US military base.

At the time of writing, the BIOT remains in existence. However, on October 3, a joint statement concerning the BIOT was issued by the British prime minister, Sir Keir Starmer, and the then-Mauritian prime minister, Pravind Jugnauth. The statement explained that the two governments had agreed on the outline of a new agreement providing that the “United Kingdom will agree that Mauritius is sovereign over the Chagos Archipelago, including Diego Garcia.”

This intended ceding of the BIOT would represent a major strategic misstep for the West, weakening its foothold in a key theatre of the world and threatening its military and security interests. The plans have been criticised as “virtue signalling” and “sheer political correctness” in the UK, where there is much concern that this is a naïve effort to look good on the international stage by unbundling the last remnant of the British Empire in Africa without considering the immediate, and especially the long-term, security implications. Similar fears have been expressed by the incoming US presidential administration.

The handover is not yet a done deal, with the UK government noting its “intention to pursue ratification in 2025.” The UK can still decline to ratify the agreement. This piece will explain why the completion of the handover of sovereignty from the UK to Mauritius would be a strategic blow to Western security.

The Strategic Importance of the Chagos Archipelago

The strategic importance of the Chagos Archipelago is linked to its commanding position in the middle of the Indian Ocean, the world’s third largest ocean. It is “critical to global trade, security, and geopolitics.” According to the Indian Ocean Rim Association, this is partly because of the concentration of human populations that surround the Ocean, with the littoral states being home to nearly 2.7 billion people. Moreover, the Indian Ocean sits at the centre of a spider’s web of global trade, “woven together by trade routes [and] major sea-lanes carrying half of the world’s container ships, one third of the world’s bulk cargo traffic and two thirds of the world’s oil shipments.” It is also considered to be a “vital trading hub, connecting the Middle East to Southeast and East Asia, as well as Europe and the Americas.”

The Indian Ocean’s positioning and its importance to trade, applies in particular to energy and oil flows. It is estimated that, of the world’s seven key choke points for oil transportation, three are in the Indian Ocean. The result of this is that any disruption along its trading routes will impact the entire globe’s energy security. Thus, the Indian Ocean has become one of the key security and strategic hotspots on the globe. Indeed, “at the heart of the geopolitical struggle in the Indian Ocean is the ability to sustain a … presence near the key choke points connecting its trade routes” such as the Mozambique Channel, the Gulf of Aden, the Gulf of Oman and the Strait of Malacca.

In even harder military and security terms, a strong presence in the Indian Ocean is central to maritime warfare and anti-piracy efforts. If a navy has a strong presence in the region then it can monitor all entry and exit points. This aids anti-submarine warfare and surveillance missions and facilities maritime domain awareness. A nation that boasts a strong security profile in the Indian Ocean will be an instrumental partner for the many littoral countries along its coastline, spanning Africa, the Middle East, and South Asia. In terms of piracy, the Indian Ocean is a particularly dangerous part of the world with Somali pirates alone being a key threat to global shipping and estimated to cost the global economy USD 7 billion per year. Thanks to possession of the Chagos Archipelago, the UK can play an important role in combatting piracy off the coast of Somalia. 

The US Military Base on Diego Garcia

The Indian Ocean’s strategic importance to regional and global trade and security is the reason that the UK leases the largest island in the Chagos Archipelago to the US for use as “Naval Support Facility Diego Garcia.” The base, which technically operates as a joint UK/US endeavour but which in practice is almost entirely American-operated, hosts “one third of America’s pre-positioned military forces, [allowing] US Army or the US Marine Corps to surge tanks and other heavy equipment…fly troops in [and sustain] long-range air operations…in the Middle East and south Asia. It is important as a communication station and for satellite monitoring [and] one of the main tracking stations for the GPS network is based there. The central positioning allows naval forces to remain on station for much longer than they would otherwise.”

The current UK Labour administration acknowledges that the base on Diego Garcia “plays a vital role in regional and global security.” Under the proposed handover, there will be a lease agreement whereby the UK will become, in effect, a “tenant” of Mauritius and whereby the US will effectively become a “sub-tenant.” The UK/Mauritius Joint Statement explains that “for an initial period of 99 years, the United Kingdom will be authorised to exercise with respect to Diego Garcia the sovereign rights and authorities of Mauritius required to ensure the continued operation of the base well into the next century.” The UK Foreign Secretary, David Lammy, seems content with that position saying that “in return for agreeing to Mauritian sovereignty over the entire islands, including Diego Garcia, the UK-US base has an uncontested long-term future.” He also notes that “the UK has the right to extend this” lease agreement.

Security Concerns about the Handover

Needless to say, others are far more sceptical. There is doubt about the supposed benefits the intended handover will bring and many are concerned that it may jeopardise the operation of the base and therefore the West’s strategic security interests. The basic position of the doubters is that UK sovereignty is the best guarantee of continued Western control over the Chagos Islands and its military base and that anything else would represent a dilution of tenure. Parliamentarians in the UK from the opposition Conservative party and other groups such as Reform (led by Nigel Farage) have been particularly hostile to the plans. Sir Robert Buckland (former Solicitor General of England and Wales) stated “I strongly feel that strategically it is right for the United Kingdom to maintain its presence in the British Indian Ocean Territory, the Chagos Islands.” Given the antipathy towards the deal, there are plans to challenge the handover in parliament, although in the UK parliament can generally only slow down the government’s ability to ratify treaties rather than formally veto them. This is in contrast with the position in the US where the executive requires two-thirds of senators to concur with ratification.

Serious concerns have also been expressed by the incoming Trump administration about the proposed handover. This is understandable as, after all, for the UK to cede sovereignty is akin to a landlord selling a house which a tenant still rents but with no real prospect of ensuring that the tenant can continue to live there after the sale. What if Mauritius changes its mind on the deal in the future and reneges? The UK should be particularly sceptical about promises made in the run-up to the handover of sovereignty given its experience with Hong Kong. Hence, a US Government source said president-elect Trump “has expressed a stance in principle to object to the deal if elected on the advice of the Department of Defense based on their global security posture.” More recently, it was reported that “the president-elect seeks to veto the controversial deal signed off by the prime minister and endorsed by Joe Biden.”

The people around Donald Trump seem to share his deep scepticism over the deal with both Marco Rubio (nominee for Secretary of State) and Pete Hegseth (nominee for Secretary of Defense) both having reportedly criticised the Chagos handover plan. Likewise, Mike Waltz (nominee to be the National Security Adviser) has been highly critical of the deal saying, “should the UK cede control of the Chagos to Mauritius, I have no doubt that China will take advantage of the resulting vacuum” to “gain valuable intelligence on our naval support facility in Mauritius.” In an admittedly hearsay account, Nigel Farage claimed that “Diego Garcia was described to me by a senior Trump adviser as the most important island on the planet as far as America was concerned.” All of this seems to entirely undo the UK Foreign Secretary’s claim that “in reaching today’s political agreement, we have enjoyed the full support and assistance of our close partners [in] the United States of America.” Perhaps that was true of the Biden administration, but it is certainly not true of its replacement.

The Threat of China

Underlying the incoming US administration’s fears about the UK’s planned handover of the Chagos Archipelago to Mauritius is one main consideration: China. China has been “putting more focus on the Indian Ocean over the last decade,” according to government testimony. Researchers say the country “has emerged as a strong partner for the islands and littoral countries of the Indian Ocean [the] Maritime Silk Road, under Beijing’s Belt and Road Initiative, has provided an added platform to collaborate on economic and military issues [and] in 2017, Beijing set up its first overseas military facility in Djibouti on the Indian Ocean coast.” Perhaps most worryingly, “since 2008, China has begun sending its warships to take part in antipiracy operations off the Gulf of Aden [and] after 2014, they started sending submarines along with those [for] shakedown cruises and…to develop a longer-range power-projection capability.”

Given that its interests in the Indian Ocean are already piqued, China might be tempted to see how it might capitalise on the absence of Western sovereignty over the Chagos Archipelago. Mauritius would be vulnerable to any overtures Beijing might make. This is partly because Mauritius has been the recipient of about USD 1.4 billion in Chinese development finance amounting to about 12% of Mauritian gross domestic product. This financing begs the question: “at what point, and in what circumstances, does economic dependence lead to political compliance?” Adding to these concerns is the fact that government of Mauritius, while democratic, is flawed by nepotism. Since 1959, the head of government role has oscillated between two powerful families, the Jugnauths and the Ramgoolams (with Paul Bérenger offering a brief 2-year respite in 2003-5). The current prime minister Navin Ramgoolam has been prime minister twice before and prior to that his father, Seewoosagur Ramgoolam, had served as prime minister and chief minister. An entrenched nepotistic regime is less likely to be able to resist Chinese overtures and historic Mauritian good relations with India may not be enough to stop a pivot towards Beijing.

Growing Chinese focus on the Indian Ocean coupled with Mauritian vulnerability presents a deeply uncertain future for a Chagos Archipelago outside the Western security umbrella. The UK Foreign Office seems to see no threat and believes that “we have full Mauritian backing for robust security arrangements including preventing foreign armed forces from accessing or establishing themselves on the outer islands.” That may be true today, but what about tomorrow? As one source observed, “the potential challenge when we look over a long enough time horizon is that low-probability events could come to the fore. One can only look at the Maldives, where India had a long-standing positive relationship with the Government. We then saw parties come into power that were more favourable to China than India.”

The uncertain long-term future of the Chagos Archipelago is probably why the Chagossians themselves are unhappy with the planned deal. As reported by the BBC, a group of the islanders reacted that “Chagossians are the real victims … Chagossians are not Mauritian … we are British” and Mauritius is motivated more by “territorial and maritime ambitions than any genuine care for the Chagossian cause.”

Conclusion

The Chagos Archipelago is a strategically vital component of Western security’s global footprint. It has been under continuous UK sovereignty for over two centuries. A recent deal between the UK and Mauritian governments that would transfer sovereignty from the former to the latter is in the process of being finalised. The deal would threaten the Western presence in the Indian Ocean and it is deeply unpopular with many in the UK, the incoming US administration and the Chagossian people. The only ones who stand to benefit seem to be Labour party leaders keen to garner plaudits for decolonisation, the Mauritian government who are naturally eager to gain substantial new territory (that had never been part of Mauritius prior to the colonial period) and, possibly in the longer term, the various military and security apparatuses of the Chinese military.

Elliot Winter is a Senior Lecturer (Associate Professor) in international law at Newcastle University in the United Kingdom.

Note: This is part one of an anticipated three-part series. Part two can be found here.