U.S. President Donald Trump has sharply criticized Britain’s agreement to cede sovereignty over the Chagos Archipelago to Mauritius, escalating tensions with Prime Minister Keir Starmer despite earlier U.S. backing for the deal.
The agreement, signed last year, transfers sovereignty while allowing Britain to retain control of the Diego Garcia military base under a long-term lease, preserving joint U.S.-UK operations.
Trump’s intervention has reframed the issue as a symbol of broader concerns over alliance strength and global competition.
In a social media post, Trump described the plan as an “act of GREAT STUPIDITY,” arguing it signaled weakness that adversaries would notice.
He linked the Chagos decision to his argument that Greenland must be acquired for security reasons, citing the perceived expansion of China and Russia.
The comments have strained Starmer’s previously stable relationship with Trump, which had delivered limited tariff relief and close diplomatic engagement.
The British government rejected Trump’s assessment, saying the deal was designed to safeguard national security after court rulings threatened the base’s future operations.
A spokesperson said: “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.”
Senior ministers insisted the agreement remains unchanged and emphasized continued U.S. support expressed before Trump’s inauguration.
Britain delayed finalizing the deal to allow review by the incoming administration, and U.S. Secretary of State Marco Rubio previously said Washington welcomed the arrangement.
Domestic divisions have sharpened, with opposition Conservative leader Kemi Badenoch backing Trump’s criticism and other parties urging resistance to U.S. pressure.
Diego Garcia has served as a launch point for operations ranging from strikes in Yemen to missions in Afghanistan and humanitarian deployments to Gaza.
Britain is paying Mauritius an average of £101 million a year to secure the base under a 99-year lease, a cost officials say ensures long-term stability.
Mauritius has pressed for swift implementation, with Attorney General Gavin Glover stating that its sovereignty “should no longer be subject to debate.”
Some Chagossians have opposed the deal, saying they were excluded from negotiations and remain displaced decades after their removal.
As Parliament advances legislation to implement the agreement, London is relying on diplomatic channels to manage tensions while maintaining alliance commitments.