U.S. President Donald Trump on Monday sharply criticized Britain’s agreement to cede sovereignty of the Chagos Archipelago, including Diego Garcia, home to a major U.S.-UK military base, calling the deal an act of “total weakness” and “great stupidity.”

The Chagos agreement, endorsed by Washington last year, transferred sovereignty to Mauritius while keeping the Diego Garcia base under a 99-year UK lease. Trump reversed his earlier approval in a blunt Truth Social post, writing:

Trump’s attack further strains relations with UK Prime Minister Keir Starmer, who has opposed Trump’s ambitions to acquire Greenland.

A British government spokesperson defended the Chagos deal, emphasizing it was motivated by national security: “We acted because the base on Diego Garcia was under threat after court decisions undermined our position and would have prevented it operating as intended in future.”

The Chagos Archipelago, consisting of six main atolls among over 600 islands, lies roughly 500 km south of the Maldives and halfway between Africa and Indonesia. The base at Diego Garcia has hosted operations ranging from bombing campaigns in Yemen to humanitarian aid missions in Gaza, as well as strikes against Taliban and al Qaeda targets in Afghanistan.

Senior British minister Darren Jones said the agreement was final and that diplomacy would be used to manage U.S. demands. “The prime minister has shown that private, proper British diplomacy can work,” he told BBC Radio.

The deal has also drawn criticism from some Chagossians, many of whom were forcibly displaced in the late 1960s and 1970s and now reside in Britain. They argue they were not consulted about the sovereignty transfer.

Even within the UK, voices such as Conservative Party leader Kemi Badenoch sided with Trump, calling the Chagos arrangement “terrible” and a “complete act of self-sabotage.”