UK-Mauritius Chagos Deal Removes Risk for Diego Garcia Naval Base

 

[By Euan Graham]

Mauritius is getting sovereignty over the remote Chagos Archipelago in the Indian Ocean, but Britain will continue to administer the strategically crucial island of Diego Garcia for another century, preserving the Anglo-American joint base on it.

That’s the gist of the deal between Britain and Mauritius announced on 3 October. It prompts two questions. First, do the outcomes constitute a net benefit for regional security? Second, what are the general implications for Britain’s foreign policy and regional role?

The answer to the first question is a cautious ‘yes’. The deal, still unsigned, promises to end legal uncertainty over the base caused by Mauritius’s mounting sovereignty challenge to the British Indian Ocean Territory, Britain’s official name for the Chagos Archipelago. With a 99-year lease on Diego Garcia to Britain, it also charts a clear pathway for the US military to continue unhindered operations from the island into the long term. That contributes to maintaining the balance of power in the Indian Ocean and beyond.

Washington will have to live with additional risk into the bargain, as fundamentally, unlike the UK, Mauritius is not a US ally. But the US military has bases in other non-allied jurisdictions and Mauritius will also receive significant income from the base as an incentive to maintain the agreement.

India, Mauritius’s de facto security guarantor, has given its tacit blessing to the sovereignty swap, which from its perspective is an optimal outcome. India has always been ambivalent about the residual British presence but would like the US to stay at Diego Garcia as a check on China’s strategic ambitions. India will probably seek access to the base for itself in future.

Implications for British foreign policy and its role in the Indo-Pacific will take longer to evaluate. On one hand, relinquishing sovereignty over the British Indian Ocean Territory has ended a longstanding dispute with Mauritius. The dispute exposed Britain to risk of diplomatic isolation and accusations that its stance exposed a double standard on compliance with international law. Conversely, giving up territory potentially sends a mixed signal about Britain’s commitment to the region and to its other overseas territories. Not everyone has been convinced of the validity of the Mauritian claim, despite its gathering momentum through international courts and the United Nations.

Communications around the initial announcement by the four-month-old government of Prime Minister Sir Keir Starmer were poor. A joint statement released on 3 October 2024 left basic questions about the deal unanswered, fanning anxieties that the Labour government had rushed to reach an agreement with Mauritius for unclear reasons. Former Conservative cabinet ministers quickly criticised the deal for selling out British sovereignty and for making unspecified financial commitments to Mauritius without consulting Parliament. But it was also revealed that those former ministers had opened negotiations with Mauritius two years previously.

In a subsequent statement to Parliament, Foreign Secretary David Lammy said a comprehensive deal to transfer sovereignty over the archipelago represented ‘the sole way to maintain full and effective operations’ for the base into the long term, through the lease from Mauritius.

It appears clear that the new Labour government, using internal legal advice, quickly decided that Britain was in a losing legal position and that an ‘inevitable’ binding judgement would force it either to abandon the base or break international law. Believing that its negotiating leverage with Mauritius was in terminal decline, the government apparently believed it had to strike a deal on the best possible terms as soon as possible.

Lammy has stressed that the deal includes a number of ‘robust security arrangements’ governing the base. Chief among these are:

—A carve-out for Diego Garcia that will preserve the administrative status quo for the base’s operations on the island, with Britain effectively taking a caretaker role and exercising ‘sovereign rights and authorities in respect of Diego Garcia’ on behalf of Mauritius; and

—Mauritius preventing ‘foreign armed forces from accessing or establishing themselves on the outer islands’ of the Chagos Archipelago.

The latter commitment could still conceivably leave the door open for grey zone activity by a hostile power, such as China, in surrounding waters. How Mauritius plans to provide maritime security for the Chagos Archipelago at large is therefore an important missing detail. There may be a role for India in this regard.

Lammy’s observation that the United States had ‘strongly encouraged us to strike a deal’ is telling, as is his observation that legal uncertainty was already weighing on operations at the base at Diego Garcia, delaying ‘critical investment decisions’.

The Biden administration did not simply endorse the deal after the fact. It has been central to the process. Senior White House officials have consistently lobbied their British counterparts about Diego Garcia. US pressure behind the scenes was apparently instrumental in kick-starting negotiations with Mauritius under the previous British government, despite its initial reluctance. All aspects of the deal have seemingly been thoroughly washed through an interagency process in the US.

Legal risk was perceived to be the primary factor. Since Mauritius obtained a favourable opinion from the Internation Court of Justice in 2019, parts of the UN machinery have been operating on the basis that Mauritius has sovereignty over Diego Garcia. British and US officials were concerned that further legal action by Mauritius could hamper base operations. For example, by jeopardising access for commercial aircraft, making it harder to bring in civilian contractors to undertake repairs, Mauritius could disrupt operations at the base. This threat was not seen as notional but as a real risk in the short to medium term.

Political risk was a significant compounding factor, as both Mauritius and the United States face elections in November. This helps to explain the compressed timing of the negotiations.

Compliance with international law dovetails with Lammy’s ‘progressive realism’. But he and the government have emphasised that the overriding factor driving the decision to retreat from sovereignty was not soft power but hard power and the determination to avoid disrupting operations at the base.

The public narrative around the dispute with Mauritius has largely been dominated by its framing as a decolonisation issue. The plight of the Chagossian people, who were forcibly removed from the archipelago to make way for the construction of the base in the late 1960s, has received keen focus. However, British officials have also had to weigh the uncomfortable prospect that the US military, as the nominal lessee, could ultimately decide to vacate the base in favour of an alternative location. That would leave Britain as the sovereign landlord with costly liabilities associated with the base and an escalating legal dispute with Mauritius to deal with. Although the ‘footprint of freedom’ may be a joint British-US facility in name, in reality it is overwhelmingly used by the US military.

Right from the start, the British Indian Ocean Territory’s expedient existence has owed more to bargaining within the Anglo-American alliance than considerations of British sovereignty for its own sake. Because of this, there is a prevailing sentiment within the British foreign policy establishment that the Chagos Archipelago is not a real overseas territory, or that it is, at least, unique. It should not be surprising, therefore, that British negotiators might feel relieved to bid goodbye to the issue.

Lead negotiator Jonathan Powell’s dismissive description of the archipelago as ‘tiny islands … where no-one actually goes’, though ill-advised, is probably widely shared within government. The problem with this sentiment, however, is that sovereignty is an irreducible concept. How the Indian Ocean territory is ceded also matters for the Falkland Islands and Gibraltar, which are claimed by Argentina and Spain, respectively. Britain’s Indo-Pacific partners will also be gauging the deal in the light of the Labour government’s willingness to remain regionally engaged.

On balance, consigning the legal distractions and bad publicity associated with the British Indian Ocean Territory to the past is a net plus for Britain’s Indo-Pacific policy. Assuming the deal is signed and ultimately ratified by Parliament, Britain’s only remaining possession in the Indo-Pacific will be the even more remote and much less strategically located Pitcairn Islands in the South Pacific. Hopefully, a final and amicable settlement with Mauritius will enable Britain to concentrate on the real prize—deepening its partnerships across the Indo-Pacific at large—while the base at Diego Garcia goes about its important business much as it did before.

Euan Graham is a senior analyst at ASPI. This article appears courtesy of The Strategist and may be found in its original form here.