Today, the islands host approximately 4,000 individuals, the majority of whom are military personnel.
Why is the UK returning the islands?
The UK had faced increasing international pressure to transfer sovereignty of the islands to Mauritius, and agreed to do so in October 2024.
Mauritius has claimed sovereignty over the islands since the 1980s and had pursued its case through international courts.
The International Court of Justice said in 2019 that Britain had illegally split the islands and should relinquish control.
In May, the UK said it agreed to pay Mauritius around £101 million ($201.6 million) per year to secure the future of the Diego Garcia military base under a 99-year lease.
Canada, Australia, New Zealand and India backed the agreement.
What did the US previously say about the deal?
When the deal was announced, the US state department said it “welcomed the historic agreement”, commending both countries for “their leadership, vision, and commitment to ensure that Diego Garcia remains fully operational for the duration of this agreement”.
It said the Trump administration had determined the agreement would secure the “long-term, stable and effective operation” of the military base.
When Trump met with UK Prime Minister Keir Starmer in February, the US president said he was inclined to support the agreement and had a “feeling” it was going to “work out very well”.
A spokesperson for the UK government said their position hadn’t changed and the agreement, which is in the final stages of being scrutinised in parliament, would still go ahead.
“This deal secures the operations of the joint US-UK base on Diego Garcia for generations,” the spokesperson said.
London-based Chagossians have previously protested against the plan, with some saying their community hasn’t been included in decisions about the island’s future.
What could be behind Trump’s shift?
His reversal follows days of European backlash and heightened tensions as Trump has ramped up his push to acquire Greenland.
Trump has threatened to impose tariffs on the UK and other European allies for opposing his claims to the autonomous territory of Denmark.
Hours before Trump’s post about the islands, Starmer held a press conference criticising the US leader for his threats to impose tariffs on allies who were against his position on Greenland.
“Shockingly, our ‘brilliant’ NATO Ally, the United Kingdom, is currently planning to give away the Island of Diego Garcia, the site of a vital U.S. Military Base, to Mauritius, and to do so FOR NO REASON WHATSOEVER,” Trump wrote in his Truth Social post.
He said there was no doubt that China and Russia were paying attention to this “act of total weakness”.
UK welfare secretary Pat McFadden said Trump’s reaction was about Greenland.
““I think what we saw last night was a series of posts criticising a number of world leaders. That may tell us that the president is frustrated right now.
“I don’t really believe this is about Chagos, I think it’s about Greenland, and the best way to resolve that is through dialogue with the Danish government, and that’s what we’ve said all along.”
— With additional reporting from the Agence France-Presse and Reuters news agencies.
