The British government has suspended legislation to transfer sovereignty of the Chagos Islands to Mauritius after U.S. President Donald Trump called the agreement a “big mistake,” putting the future of a key U.S.-U.K. military base into renewed uncertainty.

In May 2025, the U.K. and Mauritius signed a treaty to transfer to Mauritius the sovereignty of the Chagos Islands, which are home to the U.S.–U.K. base at Diego Garcia. Under the agreement, the U.K. would lease back Diego Garcia and continue operating the joint base for at least 99 years, with possible extensions.

The British government, which previously said the deal “couldn’t go ahead without U.S. support,” acknowledged Saturday that legislation to ratify the agreement has run out of time in Parliament. 

Trump earlier described the deal as the best deal U.K Prime Minister Sir Keir Starmer could make, but in February just before the U.S. started its military campaign against Iran, he said it was a “big mistake.”

Trump said transferring the sovereignty of the Chagos Islands to Mauritius could leave Britain exposed to a potential attack from the “highly unstable and dangerous” Iranian regime.

A British government spokesperson said ensuring the long-term operational security of Diego Garcia would remain a priority.

“Diego Garcia is a key strategic military asset for both the U.K. and the U.S. Ensuring its long-term operational security is, and will continue to be, our priority – it is the entire reason for the deal.” 

The spokesperson added that the government would only proceed with the deal with U.S. support.

“We continue to believe the agreement is the best way to protect the long-term future of the base, but we have always said we would only proceed with the deal if it has U.S. support. We are continuing to engage with the U.S. and Mauritius.”

Mauritius scheduled talks with U.K. officials for April 22 to pursue decolonization of the territory.