US President Donald Trump lambasted Britain's deal to cede sovereignty of the Chagos Archipelago – including an island with an important US-UK air base – as an act of "total weakness" and "great stupidity" underlining why he wants to acquire Greenland.

Only eight months ago Washington gave its blessing to the deal, which returned the Indian Ocean islands to Mauritius but retained UK control of the base on Diego Garcia, easily the largest of the archipelago's atolls, under a 99-year lease.

But Trump reversed that with a typically blunt Truth Social post saying: "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 added: "The UK giving away extremely important land is an act of GREAT STUPIDITY, and is another in a very long line of National Security reasons why Greenland has to be acquired."

Trump's attack heaps new strain on relations with UK Prime Minister Keir Starmer, who this week spoke out against US ambitions to take over Greenland by any means.

Responding to Trump's Chagos comments, the British government said the deal was made precisely for national security reasons. 

"We acted because the base on Diego Garcia was under threat after court decisions undermined our position and would have prevented it operating as intended in future," a spokesperson said.

Where is the Chagos Archipelago and what is its history?  

The Chagos' six main atolls, among more than 600 islands, lie 500 kilometers south of the Maldives and halfway between Africa and Indonesia. It is believed that there were no permanent settlers before European exploration. 

The archipelago became a French colony but was ceded to the UK by the 1814 Treaty of Paris.  

In 1965, the UK split the administration of the Chagos Archipelago away from Mauritius – then a self-governing UK colony, but soon to be granted independence – and formally established it as an overseas territory. 

In the late 1960s and 1970s, up to 2,000 indigenous Chagossians were forcibly displaced to establish the US-UK base on the Diego Garcia atoll.

Military operations launched from Diego Garcia in the 21st Century range from attacks against Taliban and al Qaeda targets in Afghanistan in 2001, through humanitarian aid deployments to Gaza, to bombing strikes against Houthi targets in Yemen in 2024 and 2025.

In May 2025 the UK granted sovereignty of the archipelago to Mauritius, which it is paying $136 million per year to secure the military installation.

Didn't the US approve this deal last year?

British senior minister Darren Jones said the Chagos deal was already done and he could not see how it might be changed.

Britain had in fact delayed signing the deal until after Trump's inauguration in January 2025 to give his administration time to examine the plan – and when the deal was announced last May, it was to a chorus of approval from Washington. 

Announcing the agreement in May last year, Starmer said "President Trump has welcomed the deal along with other allies, because they see the strategic importance of this base and that we cannot cede the ground to others who would seek to do us harm."

Meanwhile, US Secretary of State Marco Rubio said "President Trump expressed his support for this monumental achievement," noting the deal "reflects the enduring strength of the US-UK relationship".

"We stand ready to continue our collaboration to promote peace, security, and prosperity in the Indian Ocean and beyond," he added.

Trump himself had spoken positively about the impending deal three months previously, during Starmer's February visit to the White House. 

"They're talking about a very long-term, powerful lease, a very strong lease, about 140 years actually," Trump said. "That's a long time, and I think we'll be inclined to go along with your country."

Under the Chagos deal as agreed, the UK is expected to lease Diego Garcia for 99 years, with an option for a 40-year extension.