The United Kingdom is reviewing a proposed agreement to transfer sovereignty of the Chagos Islands to Mauritius after U.S. President Donald Trump publicly opposed the plan. U.K. Defence Secretary Wes Streeting stated on Wednesday, Sept. 23, 2026, that the government must conduct the review because the United States does not support the current terms. The original deal would have seen the U.K. cede control of the territory while leasing back a strategic military base on the island of Diego Garcia.
The Chagos Islands, a group of approximately 60 islands, have been a British overseas territory since 1965, when they were separated from Mauritius prior to its independence. Between the late 1960s and early 1970s, the U.K. forcibly removed more than 1,000 residents to facilitate the construction of a joint U.K.-U.S. military base on Diego Garcia. In 2019, the International Court of Justice issued an advisory ruling stating the U.K. should end its administration of the islands, leading to a formal agreement between Mauritius and former U.K. Prime Minister Sir Keir Starmer in May 2025.
President Trump characterized the agreement as a "terrible deal" during remarks at the United Nations General Assembly, questioning why sovereignty would be granted to a party that had not exercised ownership for "decades and centuries." The president emphasized the strategic necessity of Diego Garcia, noting that U.S. B-2 bombers recently had to fly from Missouri to conduct strikes on Iranian nuclear sites rather than using the Indian Ocean base. U.K. Prime Minister Andy Burnham met with Trump in New York earlier this week, though the U.K. government had already paused the deal in April 2026 following pressure from the Trump administration.
The review affects the sovereignty of the Chagos Islands and the legal status of the roughly 1,000 people and their descendants who were displaced from the territory. If the deal remains paused or is canceled, Mauritius—which claims the islands as its own—may seek alternative international partnerships. Ben Judah, a former Foreign Office advisor, suggested that if the U.K. cannot finalize the deal, Mauritius might invite Chinese investment in the surrounding atolls, potentially leading to the establishment of Chinese listening stations or fishing operations in a region currently dominated by U.S. and British military interests.
For U.S. taxpayers and military personnel, the deal involves a financial and operational commitment. The proposed agreement required the U.K. to pay Mauritius an average of £101 million ($136 million) per year to lease the Diego Garcia base over a 99-year period. Strategically, the base serves as a launch point for U.S. operations in the Middle East and the Indian Ocean. A failure to reach a diplomatic consensus could complicate the 1966 bilateral military treaty between the U.S. and the U.K., which requires an exchange of diplomatic notes to finalize any changes to the status of the base.
The deal has never been formally approved by the British Parliament, and the U.S. State Department has not yet issued the necessary diplomatic note to allow the sovereignty transfer to proceed. Observers, including Judah, noted that the U.K. may wait for the results of the upcoming U.S. midterm elections in six weeks to see if the political landscape in Washington shifts. No specific end date for the U.K. review has been set.