There is real confusion over Diego Garcia and the UK-Mauritius deal in London this summer. Is the agreement dead, alive, or something in between, like some diplomatic Schrodinger’s cat? Britain’s new prime minister, Andy Burnham, began by insisting the deal remained government policy. Days later, his defense secretary, Dan Jarvis, cast doubt on that at the despatch box in parliament, openly weighing whether the £35 billion ($48 million) earmarked for Port Louis might instead plug gaps in UK defense spending. What Foreign Office officials are telling nervous Mauritian counterparts in Port Louis, evidently, is not what ministers are discussing in Parliament.
The deal, signed in May 2025, remains unratified 14 months on, caught between domestic political opposition, a geopolitically minded policy community, human rights lawyers, and London firms that have not been above representing Mauritius against His Majesty’s Government. To understand why it has stalled, and whether it deserves to be revived, it helps to ask a question London has mostly avoided: Was this deal ever actually lawful, or merely inevitable given who controlled the process that produced it?
A dependency, not a colony
The Chagos Archipelago was uninhabited until the French introduced slave labor to work its copra plantations in 1793. It passed to Britain under the 1814 Treaty of Paris and was administered, for convenience, as a “dependency of Île de France,” later Mauritius. In 1968, at the height of the Cold War, London detached the archipelago from newly independent Mauritius so it could work with Washington to build an air base on Diego Garcia. London’s administrative tidy-up produced the British Indian Ocean Territory (BIOT); the Chagossians themselves were expelled, and the islands passed to fifty years of rotating US and UK airmen.
That administrative convenience became, decades later, the basis of Mauritius’s claim. In 2019 the International Court of Justice issued a non-binding advisory opinion holding that Mauritius’s decolonization had not been “lawfully completed” in 1968. The UN General Assembly followed with Resolution 73/295, declaring Chagos “an integral part of the territory of Mauritius.” And then in 2021, ITLOS Special Chamber ruling in the Mauritius-Maldives maritime boundary case treated the ICJ’s opinion as settled, closing off what remaining ambiguity London had relied on.
Who was doing the deciding
What deserves more scrutiny than it has received is how that process was engineered. Mauritius’s claim was built and sustained inside the UN Special Committee on Decolonization, the C24, a body chaired and populated by China, Russia, Cuba, Syria, and Iran among others. These are not disinterested custodians of self-determination. The same states pushing for the “liberation” of American Samoa, Guam, New Caledonia, the Falklands and the US Virgin Islands have shown no comparable enthusiasm for Hong Kong, Tibet, Xinjiang, Macau, Crimea, Dagestan or Chechnya, all quietly absent from the list. Mauritius’s case did not simply persuade the General Assembly on its merits; it moved through a decolonization legal architecture that actively excluded “imperial” Britain from defending its sovereign claims. It is a unique legal framework within international law and was arguably weaponized against Britain by a cabal of states.
Against that backdrop, the legal case for the deal looks considerably thinner than London has allowed. Two problems stand out. First, decolonization has not traditionally returned administrative dependencies to the states that once managed them; dependencies more commonly become separate states of their own, particularly where linguistic, cultural and political ties are as attenuated as those between the Chagossians and Mauritians. Second, and more troubling, Mauritius’s claim has been allowed to override the self-determination rights of the Chagossian people themselves, who were consulted by neither London nor Port Louis at any stage. As one Chagossian NGO put it to a parliamentary inquiry, there is “no real reason to simply hand Mauritius the islands because they were part of a colonial package,” and it is “utterly wrong to determine the future of the islands without the Chagossian people being at the center of decision making.”
Where Washington fits in
The Special Relationship complicates rather than clarifies matters. Donald Trump’s administration has raised the prospect of blocking the deal outright, a red line British officials are desperate not to cross. That represents a genuine reversal: the Biden administration backed the agreement explicitly to “defend the rules-based order,” and even Trump’s own State Department, through Secretary Marco Rubio, initially voiced support before the administration’s position hardened around the deal’s basing and security risks. Whatever one makes of that inconsistency, it is now the decisive fact on the ground: without Washington’s sign-off, ratification does not happen, whatever Whitehall tells Port Louis.
A deal without a mandate
Strip away the diplomatic noise and the deal currently has no constituency that actually wants it in its present form. The Chagossians oppose it. A defense secretary is publicly weighing whether to spend the money elsewhere. The Americans have stalled it. And the legal architecture that produced Mauritius’s claim was built inside a body whose members have every interest in weakening Western basing rights and none in applying the same standard to their own contested territories.
Burnham’s government has a choice that is more consequential than “revive or abandon.” It can renegotiate toward binding guarantees on base security and a genuine Chagossian consent mechanism, formalizing something closer to the Falklands model than the current arrangement offers. A fair referendum among all Chagossians would be a good start. Or it can allow the deal to drift in ratification limbo, which satisfies nobody and leaves the UK’s word with even less worth in Washington, Port Louis and with the Chagossians. Schrödinger’s cat will eventually have to be removed. London should do what it did with the Falklands Islands and hold a referendum and, should that keep Diego Garcia British, negotiate basing rights with a partially resettled population that will need the base for economic survival.
John Hemmings ([email protected]) is Director for the National Security Center at the Henry Jackson Society and Senior Advisor at Pacific Forum.
Media: AP Photos
The Pilot commentaries and responses represent the views of the respective authors. Alternative viewpoints are always welcomed and encouraged. Please write to [email protected] for more information on how to contribute.