Trump Again Warns Starmer Not to ‘Lose Control’ of Chagos Islands, Citing Iran Risk

President Donald Trump warned U.K. Prime Minister Keir Starmer against handing over the sovereignty of the Chagos Islands to Mauritius, arguing it could leave Britain vulnerable to a potential attack from the “highly unstable and dangerous” Iranian regime.

Diego Garcia of the Chagos Islands is currently home to a strategic U.K.-U.S. military base—a fact Trump referred to in his statement.

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“Should Iran decide not to make a deal, it may be necessary for the United States to use Diego Garcia and the airfield located in Fairford, in order to eradicate a potential attack by a highly unstable and dangerous regime—an attack that would potentially be made on the United Kingdom, as well as other friendly countries,” Trump claimed.

Accusing Starmer of making a “big mistake,” Trump said the U.K. leader “should not lose control, for any reason, of Diego Garcia.”

The warning comes as speculation mounts about possible U.S military action against Iran.

Amid heightened tensions, the U.S. has escalated its military buildup in the region. American officials held talks in Geneva with Iranian counterparts over Tehran’s nuclear program earlier this week, but they remain “very far apart on some issues,” according to White House press secretary Karoline Leavitt.

TIME has contacted the White House for further comment.

The Chagos Islands became British territory in 1814, when they were ceded to the U.K. along with Mauritius. The islands were separated from Mauritius in 1965, when Mauritius was still a British colony, and were purchased as an overseas territory by the U.K. for roughly £3 million ($4 million). Since Mauritius gained independence from the U.K. in 1968, its leadership has argued it was illegally forced to give away the land in order to get independence from Britain. Under a deal signed last year, the U.K. agreed to transfer sovereignty to Mauritius while leasing back the strategically-significant Diego Garcia base.

“Starmer is losing control of this important island by claims of entities never known of before. In our opinion, they are fictitious in nature,” Trump said Wednesday, adding that if the deal is, in fact, followed through, it’ll be a “blight” on the U.K.

In response, a spokesperson for the U.K. Foreign Office told TIME: “The deal to secure the joint U.K.-U.S. military base on Diego Garcia is crucial to the security of the U.K. and our key allies, and to keeping the British people safe. The agreement we have reached is the only way to guarantee the long-term future of this vital military base.”

U.K. lawmaker Alex Davies-Jones on Thursday said the U.K. will move ahead with the bill, despite Trump’s hesitations.

“We will continue to work with our allies, including the Americans, on this but first and foremost the priority must be national security and that is what this government is determined to deliver,” she told Times Radio.

Trump’s disapproval of the leasing appears to contradict a statement issued by the U.S. State Department on Feb. 17, which directly expressed support for the U.K.’s decision to proceed in its agreement with Mauritius concerning the Chagos Archipelago.

Trump’s personal position on the deal has shifted in recent months.

When Starmer visited Washington in February 2025, Trump told him he thought it would “work out very well” and described the proposed arrangement as “a very long-term, powerful lease.”

But in January, when doubling down on his push to acquire Greenland, he lashed out at the U.K.’s own geopolitical moves, calling the islands agreement “an act of great stupidity,” one of “total weakness.”

Trump walked back his strong stance a few days later, saying he had spoken with Starmer and understood the deal was “the best he could make.”

“However, if the lease deal, sometime in the future, ever falls apart, or anyone threatens or endangers U.S. operations and forces at our base, I retain the right to militarily secure and reinforce the American presence in Diego Garcia,” he warned.

Trump’s latest comments come ahead of talks planned for next week between the U.S. State Department and Mauritius on the strategic base at Diego Garcia.