Why the Diego Garcia Deal Makes Sense

 

The British Government and the Government of Mauritius have, in principle agreed a deal to hand over sovereignty of the Chagos Archipelago, while retaining the right for British and American forces to continue to operate out of the military base in Diego Garcia. There has been considerable controversy around it in the UK, with it being seen as a form of ‘sell out’ or risk to national security for British and American interests, while benefitting China in the long run. Concerns have also been raised about the cost of the arrangements, with the UK paying an average of £101m per year to retain the site over 99 years.

The counter view to this is that the deal represents a pragmatic outcome that ensures the UK retains access to the island facilities, while ensuring it remains on the right side of international law.  From a UK perspective the long-term legality of sovereignty had been under challenge following a series of rulings by the International Court of Justice, and the UN General Assembly demanding the UK hand over sovereignty. While the UK could have chosen to ignore these calls, to do so would potentially have left the UK exposed in the UN and weakened its ability to call for national determination elsewhere. Look at the Ukraine conflict, where the British Government has been steadfast in defending the rights of Ukraine to defend, and retake its territory against Russian attack. To support this to the extent of providing weapons, and vast materiel support, while ignoring equally compelling demands to hand over BIOT to Mauritius would be difficult.

The deal to hand all the archipelago other than Diego Garcia to Mauritian control represents a pragmatic reality check. The UK has no wider strategic or economic interest in those islands, they are uninhabited and practically uninhabitable, and while protected for marine conservation purposes, do not hold any other value. Possession of the wider Chagos archipelago does not, of itself, provide meaningful benefit for the taxpayer.

HMS TAMAR crew on island 2023 (MOD Crown Copyright)

The deal enables the UK and US to retain a presence, initially on a 99-year term as a form of ‘lease’ enabling continued operations under an internationally binding treaty. The clear benefit here is that this removes legal ambiguity and safeguards the miliary presence. By placing it under a treaty, it makes it far harder to break or amend, and it is likely some legally robust language will be in place to prevent this occurring. The result will be that operations continue, uninterrupted and legally safeguarded for at least a century.  This is far more sustainable than the current position and weakens our opponents’ hands.  It is likely that both Russia and China used the BIOT issue to sow discord with our traditional allies, trying to influence and shape opinions against us. By amicably resolving this, it makes it harder to disrupt our presence in this way.

From an operational perspective, there will be remarkably little impact for the UK. Diego Garcia has long been a backwater for the Royal Navy. Other than limited use in WW2 for RAF maritime patrols, it is today rarely used by RN vessels, between 2008 and 2024, records indicate that only four ships visited (PROTECTOR, SUTHERLAND, TAMAR and TRENCHANT) the island has been too far from major shipping routes or operational areas.  The sole maritime asset is the BIOT protection vessel, a former tug, chartered to patrol the Chagos islands.

While some may like to think of Diego Garcia as a UK base, it is an American base with a tiny British element. The current UK presence is around 30 strong, comprising a small naval party (NP1002) to carry out customs, immigration and policing, as well as support fishery protection patrols. It is unclear if NP1002 will remain post deal, and the most likely use of the facility for the UK in future will be for occasional use by SSN visits.

In practical terms, handing over sovereignty will not impact on the Royal Navy’s ability to operate in the Indian Ocean. Diego Garcia does not house any permanent military capabilities to conduct operations. It is many weeks of sailing time from the UK, and at least a week from either Bahrain or Singapore. There are no stores, supplies or RN munitions held there, so as a facility, it is of limited military value in a UK operation, as the shooting is likely to be over before the assets reach the island, let alone deploy again for operations.

The deal puts our presence in Diego Garcia on similar terms as those of our facilities in Bahrain, Oman and Singapore – naval facilities over which the UK has considerable operational autonomy and control. All these facilities are arguably far more important to our naval power and capabilities than Diego Garcia and used far more regularly. We have highly limited sovereign authority over any of them but can use them as needed.

Diego Garcia

There have been concerns raised about the fact that the UK will notify Mauritius ‘expeditiously’ of the use of the facility for military purposes. There are two points to note, firstly, there is no timeline attached to ‘expeditious’ and secondly this is not uncommon for foreign basing agreements that the visiting nation advises the host nation when the facility is used. There is nothing here that prevents the facilities from being used when needed, as Mauritius has no veto over the sites use.

There is a wider danger that the arguments over sovereignty are being conflated with suggestions that Mauritius may open the door to China or other powers establishing listening posts nearby, or that the site will become an easier target in wartime. The nearest other islands are a significant distance from Diego Garcia, are tiny and have never been inhabited as they lack the ability to support human life. It would be next to impossible to build a listening post on the islands without it being easily detected. The proposed treaty has legally binding obligations in place to prevent such construction occurring anyway, giving the UK a veto on construction, and preventing military facilities being built on outlying islands.

Construction of a building does not mean it becomes an intelligence hub of value. To be certain of valuable collection, China would need to monitor shipping and aerial movements in real time using AGIs, much as the Soviet Union did during the Cold War. During the Vietnam War, for example, the Soviets maintained AGI’s off the coast of Guam, reporting on both warship movements and launches of air strikes, providing invaluable real time intelligence to Vietnamese air defence forces. This was carried out quite legally just outside of territorial waters. There is absolutely nothing to stop China or Russia carrying out a similar activity today, even if the UK retains sovereignty of Diego Garcia. Russian AGI’s have patrolled off UK waters collecting intelligence for many decades. It is also difficult to imagine that potential foes do not already have plans to strike Diego Garcia in the event of a major conflict.

One concern raised by opponents is that the deal is for ‘only’ a 99-year lease of Diego Garcia, versus our current long-term occupation of the islands. A century is a remarkably long time in international politics.  In 1925 Diego Garcia was an irrelevance for defence purposes and we have no idea of what the world in 2125 will be like or who the major powers are. It may be the case that there is no further need for Diego Garcia for defence purposes, or that Mauritius may wish to retain the leaseback arrangement, judging it to be in its national interests to do so. The arrangement signed provides the flexibility for all parties to reach informed decisions decades from now.

If the deal is agreed, then what is to stop Mauritius reneging on it? In practical terms nothing, but this is the way with all legally binding treaties. But Mauritius is also likely to accept that incurring the enmity of the UK and USA and breaking international law by rowing back on a treaty willingly entered in to is unlikely to be sensible. Furthermore, there is nothing they could practically do to evict the US from the island.

The reality is that, for the UK, Diego Garcia is of very limited strategic interest or value of itself, but it is an invaluable tool for the United States. The outcome here is about securing a deal that benefits the USA’s long term strategic presence in the Indian Ocean. This arrangement should provide the legal certainty to allow ongoing operations to continue without disruption, free from complex legal challenges, and without the risk of breaking international law in the process. In practical terms, nothing changes, it is ‘business as usual’ but on a stable and secure long-term footing.  This is a good deal for the UK and USA and secures Diego Garcia's future as a vital part of Western defences for at least a century to come – we should welcome it, not reject it.

 

Sir Humphrey is a former civil servant with over 25 years’ experience working in Defence, Intelligence and National Security related roles across Whitehall and beyond.  He visited Diego Garcia in 2003.