What is the UK's Chagos Islands deal and what has Trump said about it?

US President Donald Trump has said the UK should "not give away Diego Garcia" in his latest criticism of a deal to hand over the Chagos Islands to Mauritius and lease back a key military base.

His words came a day after the US had backed the UK's £3.4bn ($4.6bn) agreement, in which he UK would lease Diego Garcia, the largest island in the archipelago, and home to the joint UK-US base.

The president had previously criticised the deal as "an act of GREAT STUPIDITY", but had then said it was the "best" Sir Keir Starmer could make.

The Chagos Islands - officially known as the British Indian Ocean Territory - are located in the Indian Ocean about 5,799 miles (9,332km) south-east of the UK, and about 1,250 miles north-east of Mauritius.

Also known as the Chagos Archipelago, there are around 60 individual islands, grouped together in seven ring-shaped coral atolls. The islands were separated from Mauritius in 1965, when Mauritius was still a British colony.

Britain purchased the islands for £3m but Mauritius has argued that it was illegally forced to give them away as part of a deal to gain independence from Britain.

In the late 1960s, Britain invited the US to build a military base on Diego Garcia, forcibly removing thousands of people from their homes in the process.

Some of those Chagossians ended up in Mauritius and the Seychelles, but others settled in the UK, mostly in Crawley, West Sussex.

The UK will hand sovereignty of the archipelago to Mauritius, and lease back Diego Garcia for a period of 99 years - at an average cost of £101m a year.

The UK will pay £165m in each of the first three years. From years four to 13, it will pay £120m a year. After that, payments will be linked to inflation.

Announcing the deal, Sir Keir said the continued use of Diego Garcia was necessary to protect the base from "malign influence". He said the US would pay the base's "running costs".

The agreement also includes a £40m trust fund to support Chagossians.

Under the deal, although Mauritius will control Diego Garcia, it will not be allowed to resettle the island.

The deal has been heavily criticised by the Conservatives and Reform UK, who argue it undermines national security because of Mauritius's ties to China.

Both political parties have welcomed Trump's various comments condemning the deal.

Speaking ahead of the deal, during Sir Keir's February 2025 White House visit, Trump indicated that he was prepared to back the UK Chagos plan.

When the deal was finally agreed in May, US Secretary of State Marco Rubio said Trump had "expressed his support for this monumental achievement".

However, writing on the Truth Social website in January 2026, Trump called it an "act of total weakness".

He wrote: "Shockingly, our 'brilliant' NATO Ally, the United Kingdom, is currently planning to give away the Island of Diego Garcia, the site of a vital US Military Base, to Mauritius, and to do so FOR NO REASON WHATSOEVER."

He said the agreement was among a "very long line of National Security reasons" underpinning his efforts to acquire Greenland from Denmark.

At the time, Sir Keir insisted the the UK's position on the Chagos Islands had not changed, and accused Trump of trying to pressure the UK to soften its support for Greenland.

Mauritian Attorney General Gavin Glover said the sovereignty of the Chagos Archipelago "should no longer be subject to debate".

"We expect the treaty to be implemented as soon as possible, in accordance with the commitments made," he added.

In early February, Downing Street said Trump and Starmer had "agreed on the importance" of the deal during a phone call.

Writing on Truth Social, Trump called the discussions "very productive", adding: "I understand that the deal Prime Minister Starmer has made, according to many, the best he could make."

But on 18 February the president criticised the deal again, saying that "leases are no good when it comes to countries", and that Sir Keir risked making a "big mistake" about the "strategically located" island.

Referring to ongoing US-Iran talks on Tehran's controversial nuclear programme, he said if a deal was not agreed, the base might be needed "in order to eradicate a potential attack by a highly unstable and dangerous Regime", which he said could also target the UK.

"This land should not be taken away from the UK and, if it is allowed to be, it will be a blight on our Great Ally," Trump added.

On 25 February Foreign Office Minister Hamish Falconer told MPs that following interventions from the president, the government was now "discussing those concerns with the United States directly".

The process to ratify the deal would pause to allow further negotiations, he said. It would be brought back to Parliament "at the appropriate time," he added.

But shortly after a government source said "there is no pause, we have never set a deadline and timings will be announced in the usual way".

Diego Garcia is the largest of the Chagos Islands.

Since the early 1970s, the UK and the US have jointly run a secretive military base there. The government says its facilities include an airfield and deep-water port, as well as advanced communications and surveillance capabilities.

There are no commercial flights to the island. Access is granted by the military facility or, previously, the British authority that ran the territory.

Diego Garcia is seen as having high strategic important because of its location in the heart of the Indian Ocean.

During the US "war on terror" after the 9/11 attacks, aircraft were sent directly from the island to carry out missions in Afghanistan and Iraq.