What are the Chagos Islands and why does Trump think Britain would be stupid to give them up?

By Christian Edwards, CNN

(CNN) — Donald Trump has accused the United Kingdom of “stupidity” over its plan to hand over ownership of the Chagos Islands, including the US air base on Diego Garcia, to Mauritius.

“Shockingly, our ‘brilliant’ NATO Ally, the United Kingdom, is currently planning to give away the Island of Diego Garcia … FOR NO REASON WHATSOEVER. There is no doubt that China and Russia have noticed this act of total weakness,” Trump wrote early on Tuesday morning on Truth Social.

“The UK giving away extremely important land is an act of GREAT STUPIDITY,” he added, citing the move as another reason for Washington to seize control of Greenland.

The US president’s newfound opposition to the Chagos Islands plan has reignited a fierce debate in the UK and comes despite the fact that he praised the deal last year as a “monumental achievement.”

What are the Chagos Islands?

The islands make up an archipelago in the center of the Indian Ocean, more than 1,000 miles northeast of Mauritius. The UK took over the islands along with Mauritius in 1814 under the Treaty of Paris after the defeat of Napoleon.

In 1965, a Cold War agreement between the US and UK split the Chagos Islands from Mauritius, keeping control of the archipelago and renaming it as the British Indian Ocean Territory. Over time, many Chagossians were removed from the island to create space for a military base, with most resettling in Mauritius. Although Mauritius gained independence in 1968, the Chagos Islands remain under British control.

Why does the US have a military base there?

Hoping to stave off Soviet military influence in the region, the US and UK built a major base on Diego Garcia in 1971. One of America’s most important – and secretive – overseas assets, Diego Garcia has helped launch two invasions of Iraq, served as a vital landing spot for bombers that fly missions across Asia, and has been linked to US rendition efforts.

Why is the UK relinquishing control of the islands?

Mauritius has for decades claimed sovereignty over the islands and pursued the case through international courts. In 2019, the International Court of Justice – the United Nations’ highest court – ruled that the UK must return the Chagos Islands to Mauritius “as rapidly as possible.” In its ruling, the court said the move would enable Mauritius to “complete the decolonization of its territory in a manner consistent with the right of peoples to self-determination.”

Although the judgment was non-binding, the UK has faced growing international pressure to give up control of the islands. Successive British governments – both Conservative and Labour – have argued it is a test of the UK’s commitment to international law.

Will the UK and US still have access to the islands?

Only to Diego Garcia. Under the terms of a treaty approved and signed by UK Prime Minister Keir Starmer and his Mauritian counterpart in May 2025, the UK will transfer sovereignty over all the Chagos Islands to Mauritius.

However, the UK will pay Mauritius £101 million ($136 million) each year for a 99-year lease on the military base at Diego Garcia, meaning the UK and US can still use the facility.

At the time the US State Department said Washington “welcomed” the deal between the UK and Mauritius.

“Following a comprehensive interagency review, the Trump administration determined that this agreement secures the long-term, stable, and effective operation” at Diego Garcia, US Secretary of State Marco Rubio said in a statement, adding that Trump “expressed his support for this monumental achievement” during a meeting with Starmer.

Could the deal be terminated?

Although the treaty has been heavily scrutinized by both chambers of the British parliament and is nearing final approval, Trump’s sudden opposition to the deal has spurred politicians on the British right to renew their criticisms.

“The Americans have woken up to the fact that they were lied to,” Nigel Farage, the leader of the populist Reform UK party, said Tuesday. “They were told that the UK had no choice but to surrender the Chagos Islands. This was simply not true, and now they are angry with us.”

Kemi Badenoch, the leader of the opposition Conservative party, went further than Trump, saying: “Paying to surrender the Chagos Islands is not just an act of stupidity, but of complete self sabotage.”

It is not clear, however, whether Trump’s opposition or the outrage among opposition parties will scupper the deal, since Labour has a commanding majority in Parliament.

Why did Trump call the decision stupid?

Contradicting his earlier praise, Trump said the decision would be viewed by China and Russia as an “act of total weakness.”

“These are International Powers who only recognize STRENGTH, which is why the United States of America, under my leadership, is now, after only one year, respected like never before,” he said.

What do Chagossians want?

The negotiations between the British and Mauritian governments took place without the involvement of the Chagossians. The global population of Chagossians is estimated to be around 10,000, with many living in the UK, Mauritius and Seychelles.

A poll of more than 3,600 respondents conducted by Whitestone Insight found that the global Chagossian community “overwhelmingly” backed remaining British and opposed the transfer of sovereignty to Mauritius.

What does Greenland have to do with it?

On the face of it, not much. Trump claimed that the UK relinquishing control of the Chagos Islands is “another in a very long line of National Security reasons why Greenland has to be acquired,” without elaborating.

Trump has offered several reasons why he feels Washington must seize Greenland. On Monday, the president tied his hope to acquire Greenland to his failure to win the Nobel Peace Prize, saying it meant he no longer felt bound “to think purely of peace.”

In many ways, Trump’s opposition to Starmer’s deal represents a clash of world views. While Starmer argues that the UK has a legal obligation to give up the Chagos Islands to Mauritius, Trump has made it clear he does not recognize such constraints.

Asked last week by The New York Times what can check his power on the world stage, Trump said: “There is one thing. My own morality. My own mind. It’s the only thing that can stop me.” He added: “I don’t need international law.”

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CNN’s Rob Picheta contributed reporting.