In a surprising move on Tuesday, former President Donald Trump reversed his stance on the United Kingdom’s plan to hand over control of the Chagos Islands to Mauritius. He raised concerns that such a transfer could put U.S. military operations at risk, particularly the strategic Diego Garcia base.

This change in position has been described by a defense expert as indicative of what could be termed the “new Trump Doctrine.” The expert connected Trump’s firm opposition to the Chagos agreement with his earlier ambitions to acquire Greenland, hinting at underlying fears that Mauritius might later revoke the agreement.

Trump took to his Truth Social platform to express his disapproval, labeling the U.K.’s decision regarding the Chagos Islands as “an act of great stupidity.”

“Shockingly, our ‘brilliant’ NATO ally, the United Kingdom, is currently planning to give away the Island of Diego Garcia, the site of a vital U.S. Military Base, to Mauritius, and to do so FOR NO REASON WHATSOEVER,” Trump declared. “There is no doubt that China and Russia have noticed this act of total weakness.”

Furthermore, Trump linked his opposition to the potential transfer of Diego Garcia with his previous initiative to purchase Greenland from Denmark, underscoring a pattern in his strategic geopolitical maneuvers.

“Trump has done a 180, partly because of the U.K.’s support for Denmark’s sovereign claims over Greenland and partly because of a new strategy outlined by the White House,” John Hemmings, director of the National Security Center at the Henry Jackson Society, told Fox News Digital.

“These moves are linked and part of a ‘new Trump Doctrine’” outlined in November’s National Security Strategy,” he explained.

“Diego Garcia is a potential threat to Beijing’s strategy to control vital shipping lanes between the oil-rich Middle East and China’s industrial heartland,” he added, describing how “nearly 23.7 million barrels of oil transit the Indian Ocean every day, with the base being vital in any U.S.-China conflict over Taiwan.”

President Donald Trump addresses the audience during the annual meeting of the World Economic Forum in Davos, Switzerland, Wednesday, Jan. 21, 2026. (Evan Vucci/AP Photo)

In a separate post, Trump explicitly linked the Chagos dispute to his Greenland push.

“The U.K. giving away extremely important land is an act of GREAT STUPIDITY, and is another in a very long line of national security reasons why Greenland has to be acquired,” Trump wrote.

The Chagos Islands were separated from Mauritius during Britain’s decolonization process, a move the International Court of Justice ruled unlawful in 2019. 

The U.K. later agreed to transfer sovereignty while leasing Diego Garcia back for at least 99 years at a cost of at least $160 million annually.

Diego Garcia is a hub for long-range bombers, logistics and power projection across the Middle East, the Indo-Pacific and Africa. Around 2,500 personnel, mostly American, are stationed there.

Diego Garcia, the largest island in the Chagos archipelago and site of a major United States military base in the middle of the Indian Ocean, was leased from the U.K. in 1966. (Reuters)

“If Mauritius were to offer the islands to China after taking de jure control, it would put immense pressure on the U.S. in the eyes of international public opinion,” Hemmings explained.

“After all, once Mauritius has de jure sovereignty, it can renegotiate the lease terms or even renege on the treaty at any time it wants.

“It might also provide access to the exclusive economic zone, with all of its rich fishing grounds, to Chinese fishing fleets, adding another layer of risk to U.S. Air Force operations around the island,” Hemmings said.

“At this moment, the U.S. base at Diego Garcia is thought to be secure, with Mauritius promising the U.K. (and by proxy, the U.S.) a 99-year lease, which will not, it is supposed, interfere with the operations of the air base at all. But the devil is in the details.”

Fox News Digital has reached out to the White House for comment.