Donald Trump has finally put his stamp on Britain’s controversial decision to hand sovereignty of the Chagos Islands to Mauritius — but it comes with a very loud warning attached.
While the former US president says he understands why Sir Keir Starmer pushed the deal through, he has made it clear that any threat to the joint US-UK military base on Diego Garcia would trigger an American military response.
In other words: the paperwork might be Mauritian, but the guns would still be American.
The Agreement at the Heart of the Storm
Under the agreement struck by London, Britain will formally transfer sovereignty of the Indian Ocean archipelago to Mauritius.
In return, the UK and US retain control of the strategically vital Diego Garcia base through a 99-year lease, costing $47 million (£35 million).
British ministers insist the deal locks in long-term security for one of the West’s most important overseas military assets.
Critics say it risks handing influence in the region to rivals — particularly China, which has close ties to Mauritius.
A Late-Night Trump Intervention
Trump revealed on Thursday that he had held what he described as “very productive discussions” with Starmer, posting his thoughts on Truth Social after weeks of behind-the-scenes lobbying by British officials and US intelligence figures.
“I understand that the deal [Starmer] has made, according to many, the best he could make,” Trump wrote.
But the approval quickly turned conditional.
Trump warned that if the lease agreement ever collapsed, or if US troops or operations on Diego Garcia were threatened, he would “retain the right to militarily secure and reinforce the American presence” on the island.
From Endorsement to Fury — and Back Again
The comments marked a sharp change in tone from Trump’s outburst last month, when he publicly tore into the deal despite initially backing it.
At the time, he branded the agreement an “act of great stupidity” and “total weakness,” claiming Britain was giving away the base “for no reason whatsoever.”
Trump also framed the move as a surrender that could ultimately benefit China — a warning that played well with security hawks on both sides of the Atlantic.
Starmer Hits Back Over Greenland Claims
Sir Keir Starmer did not take Trump’s criticism quietly.
The Prime Minister accused Washington of shifting its position as a pressure tactic linked to Trump’s separate bid to seize Greenland from NATO ally Denmark.
That threat, however, has since fizzled out.
The White House retreated after a fierce backlash from other Western powers, leaving the Chagos deal as the main unresolved flashpoint.
A Carefully Timed Phone Call
Despite the public row, Starmer appeared to steer clear of raising the issue directly with Trump — until a phone call earlier this week.
A Downing Street readout of the conversation said both leaders agreed to “continue working closely” to safeguard the future of the Diego Garcia base, suggesting a quieter reset behind closed doors.
‘Crystal Clear’ — But Not Everyone Is Convinced
Downing Street has repeatedly insisted that the case for the Chagos Islands agreement is “crystal clear.”
That confidence was tested after Lord Mandelson claimed there had been a serious wobble inside government.
The former US ambassador said doubts emerged in London over whether the deal could be sold to the British public — and whether it truly stacked up legally.
Mandelson Lifts the Lid on Internal Doubts
In an interview with The Times, Lord Mandelson said concerns centred on the price tag, the strength of Britain’s legal obligation to strike the deal, and whether the original case made in Whitehall was as watertight as officials claimed.
“I became aware of a serious wobble in London over the agreement and its sell-ability to the British public,” he said.
He added that he found himself squeezed from both sides — facing a sceptical US administration at one moment, and a hesitant British government at another.
What’s Next?
For now, the deal survives — backed publicly by Trump, defended forcefully by Starmer, and shadowed by warnings of military intervention if anything goes wrong.
The real test will come not in speeches or social media posts, but in whether the long-term lease holds firm and keeps Diego Garcia insulated from the growing power struggles of the Indo-Pacific.
