What Are the Chagos Islands and the Diego Garcia Base?

The islands, which Britain has agreed to hand over to Mauritius, are home to a strategically important U.S.-British military base.A photo provided by the U.S. Department of Defense showing military planes at the Diego Garcia air base in 2001. The base is used to serve U.S. Navy ships and refuel long-range bombers.Credit...Department of Defense, via Agence France-Presse — Getty ImagesJan. 20, 2026, 1:24 p.m. ETPresident Trump on Tuesday cited Britain’s decision to relinquish control over the Chagos Islands to Mauritius as one reason the United States should acquire Greenland, a semiautonomous island controlled by Denmark.“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,” Mr. Trump wrote on social media. He added that decision was an “act of GREAT STUPIDITY.”Since the colonial era, Britain had controlled the Chagos, a necklace of strategic islands in the Indian Ocean. In the 1960s, Britain began expelling the inhabitants of the more than 55 islands in the remote archipelago as part of a plan to build a strategically important air base with the United States on Diego Garcia, the largest of the islands.Mauritius, an island nation in East Africa, has claimed sovereignty over the islands since gaining independence from Britain in 1968.In 2024, the government of Prime Minister Keir Starmer of Britain, under growing legal and diplomatic pressure, agreed to hand over the Chagos Islands, which are about halfway between Africa and Indonesia, to Mauritius. The decision followed years of negotiations and a ruling by the International Court of Justice, the highest court in the United Nations, that Britain had acted unlawfully by detaching the archipelago from Mauritius’s control in 1965.Last May, the governments of Britain and Mauritius signed an agreement outlining the deal. (To go into effect, it will have to be ratified by both countries.)Under the terms of the agreement — one that members of the Trump administration at first celebrated — the United States and Britain would continue to operate the military base on Diego Garcia for an initial period of 99 years.The base, used to serve U.S. Navy ships and refuel long-range bombers, is vital because the Indian Ocean is viewed as an arena for great-power rivalry. A base in the ocean, the United States reasoned, would help keep the Soviet Union and China at bay at the pinnacle of the Cold War.In addition, Diego Garcia’s location makes it a valuable listening post for surveillance and intelligence gathering. It is also home to about 4,000 U.S. and British military and civilian contract personnel.Formal negotiations between Britain and Mauritius over the Chagos began in 2022, when the government in London was run by the Conservatives. The talks gained momentum when African countries began pressing Britain to hand over sovereignty. The islands, some said, were Britain’s “last colony in Africa.”The United States, eager to secure long-term access to the base on Diego Garcia, had privately encouraged the British government to resolve the dispute over the islands. And at the time of the deal, Secretary of State Marco Rubio praised the agreement and said that Mr. Trump had “expressed his support for this monumental achievement.”Mr. Trump’s comments on Tuesday reflected a stark U-turn from that position.But it was another example of the president citing seemingly unrelated foreign actions as an apparent pretext for his wish to take control of Greenland. Over the weekend, Mr. Trump told Norway’s prime minister in a text message that since being denied the Nobel Peace Prize — which is administered by the Norwegian Nobel Committee, an independent entity — he no longer felt obliged to “think purely of Peace” in his bid to control Greenland.Pranav Baskar is an international reporter and a member of the 2025-26 Times Fellowship class, a program for journalists early in their careers.SKIP