What to know about the Chagos Islands as Trump slams the UK's sovereignty deal

LONDON — U.S. President Donald Trump has turned his fire on a deal between Britain and Mauritius to settle the future of the Chagos Islands, the contested Indian Ocean archipelago that is home to a strategic U.S. military base.

Trump said on social media that a deal to transfer sovereignty of the islands from the U.K. to Mauritius is ''an act of GREAT STUPIDITY.''

That's despite the Trump administration previously welcoming the agreement as a way to ensure the security of the American base on Diego Garcia, the largest of the island chain.

Here's what to know about the disputed islands.

The Chagos Islands are remote but strategic

The remote chain of more than 60 islands is located in the middle of the Indian Ocean off the tip of India, south of the Maldives.

The Chagos Islands have been under British control since 1814, when they were ceded by France.

Britain split the Chagos Islands away from Mauritius, a former British colony, in 1965, three years before Mauritius gained independence, and called the Chagos archipelago the British Indian Ocean Territory.

The U.S. has described the base, which is home to about 2,500 mostly American personnel, as ''an all but indispensable platform'' for security operations in the Middle East, South Asia and East Africa.

Most recently, the U.S. deployed several nuclear-capable B-2 Spirit bombers to Diego Garcia amid an intense airstrike campaign targeting Yemen's Houthi rebels.

Why they are contested

In the 1960s and 1970s, Britain evicted as many as 2,000 people from the islands so the U.S. military could build the Diego Garcia base.

The United Nations and the International Court of Justice have both urged Britain to end its ''colonial administration'' of the islands and transfer sovereignty to Mauritius.

The British government says it struck a deal with Mauritius to protect the security of the Diego Garcia base from international legal challenge.

What's in the deal

Negotiations on handing the islands to Mauritius began in 2022 under the U.K.'s previous Conservative government and resumed after Prime Minister Keir Starmer's Labour Party was elected in 2024.

Talks dragged on amid a change of government in Mauritius and disputes over money, but the agreement was signed of in May 2025 after Britain had sought and received backing from the Trump administration.

What the reaction has been

The deal has been opposed by many opposition politicians in Britain who say giving up the islands puts them at risk of interference by China and Russia.

Conservative Party leader Kemi Badenoch said the agreement ''weakens U.K. security and hands away our sovereign territory.''

Trump now appears to agree that it is a bad deal and links it to his desire to acquire Greenland.

He wrote on social media that handing over sovereignty would benefit China and Russia and is ''another in a very long line of National Security reasons why Greenland has to be acquired.

An estimated 10,000 displaced Chagossians and their descendants now live primarily in Britain, Mauritius and the Seychelles. Many of them want to return to the islands, and some have fought unsuccessfully in U.K. courts for many years for the right to go home.

Chagossians say they were left out of the political negotiations, which have left them unclear on whether they and their descendants could ever be allowed to return to their homeland.

Human Rights Watch has said that Britain's forced displacement of the Chagossians and ongoing refusal to let them go home ''amount to crimes against humanity committed by a colonial power against an Indigenous people.''

Two Chagossian women, Bernadette Dugasse and Bertrice Pompe, who challenged the handover deal in the British courts, argued it will become even harder to return once Mauritius takes control of the islands.