The U.K. hands Chagos Islands over to Mauritius but says it will secure a U.S. base

LONDON — The United Kingdom has signed a deal to hand over sovereignty of the Chagos Islands to Mauritius, in an agreement Britain says will also ensure the future of a strategically important U.S. military base.

The Chagos Islands are an archipelago in the middle of the Indian Ocean. Under the deal, the U.K. can continue leasing the largest of the islands, Diego Garcia, keeping the key military facility in British and American hands for at least 99 years.

U.S. Secretary of State Marco Rubio welcomed the agreement between the U.K. and Mauritius and said in a statement that President Trump “expressed his support for this monumental achievement” when he met British Prime Minister Keir Starmer at the White House in February.

Starmer said the deal to secure the U.K.-U.S. military base in Diego Garcia — to be leased for more than $100 million a year — is vital for Britain’s defense, intelligence and national security.

The prime minister of Mauritius, Navin Ramgoolam, hailed the deal as a “great victory for the Mauritian nation,” and said, “We are completing the process of total decolonization.”

The deal comes after a lengthy dispute over the islands that has involved questions over Britain’s colonial legacy.

The Chagos Archipelago became a British territory in 1814. In 1965, the U.K. formally separated the islands from its then-colony Mauritius, before Mauritius gained independence three years later. In the late 1960s, the U.K. invited the U.S. to build a military base on Diego Garcia, which forced thousands of people from their homes.

But despite the U.K. paying 3 million pounds for the islands, Mauritius has argued it was illegally forced to give them away as part of a deal to gain independence from Britain. International courts have sided with Mauritius, a country of few more than 1 million people.

In a nonbinding opinion in 2019, the International Court of Justice in The Hague concluded that “the process of decolonization of Mauritius was not lawfully completed when that country acceded to independence” and that “the United Kingdom is under an obligation to bring to an end its administration of the Chagos Archipelago as rapidly as possible.”

Then in 2021, a United Nations maritime court rejected Britain’s claim to sovereignty over the islands.

Now, the U.K. and Mauritius have signed an agreement stating “Mauritius is sovereign over the Chagos Archipelago in its entirety, including Diego Garcia.”

But Prime Minister Starmer underscored the significance of being able to lease back the island where the key military base is located.

At U.K. military headquarters in Northwood, near London, Starmer told reporters that the deal was “one of the most significant contributions that we make to our security relationship with the United States.”

He said much of what the military base is used for is highly classified, but “the strategic location of this base is of the utmost significance to Britain.” He said it was important for “defeating terrorists in Iraq and Afghanistan” and helped “reduce the risks to brave British and American servicemen and women.”

The British government said the deal was backed by the U.S., Canada, Australia and New Zealand, which are part of an intelligence-sharing partnership with the U.K.

Some Chagossians, as the islands’ people are known, have expressed support for the deal, while others are strongly against it.

The largest Chagossian community in the U.K. is in Crawley, Sussex, in South East England. The town’s representative in British Parliament, Labour member Peter Lamb, criticized the deal, saying it did not secure the right for Chagossians to return to their homeland.

“What should I tell my Chagossian constituents, when they ask the moral basis upon which the U.K. is ignoring their right to self-determination while we fight for it in Ukraine for Ukrainians?” he said in Parliament Thursday.

Some opposition politicians railed against the agreement.

“The Chagos Islands have been British since 1814. Only Keir Starmer’s Labour Party would negotiate a deal where we’re paying to give something away,” Conservative Party leader Kemi Badenoch said. “This is a vital military base. Mauritius is an ally of China.”

Right-wing populist Reform U.K. party leader Nigel Farage also said the move “plays into China’s hands.”