Welcome to Foreign Policy’s Africa Brief.

The highlights this week: A landmark decision deals a fresh blow to the U.K.-Mauritius Chagos Islands deal, the Democratic Republic of the Congo inks a third-country migrant deal with the United States, and the Mali-Mauritania rift deepens amid rising border violence.

Welcome to Foreign Policy’s Africa Brief.

The highlights this week: A landmark decision deals a fresh blow to the U.K.-Mauritius Chagos Islands deal, the Democratic Republic of the Congo inks a third-country migrant deal with the United States, and the Mali-Mauritania rift deepens amid rising border violence.

A landmark legal ruling has dealt a fresh setback to the United Kingdom’s deal with Mauritius to hand back the Chagos Islands, Britain’s last African colony, after a bitter, decades-long battle.

Last week, the Supreme Court of the Chagos Archipelago—officially known as the British Indian Ocean Territory—overturned the ban on Chagossians living on the outer islands.

No Chagossian has lived permanently on any of the islands in more than 50 years. The United Kingdom detached Chagos from Mauritius three years before the latter’s independence in 1968. At the time, Britain forcibly removed thousands of Chagossians in order to build a joint U.S.-U.K. military base on Diego Garcia, the largest of the 58 islands. Most of them were resettled to Mauritius or Britain.

The military base, which is strategically located roughly halfway between Africa and Asia, aids in surveillance of the Middle East and has been critical to defensive operations in the Iran conflict and previous wars in Iraq and Afghanistan.

In February, four Chagossians arrived on Île du Coin—an atoll of the archipelago located around 135 miles from Diego Garcia—and announced their intention to live there. The British government issued eviction notices to the Chagossians and threatened fines and up to three years in prison for noncompliance, prompting the recent court case.

The judge stated that a “claimed power to exclude a whole population must be justified by legal source, not administrative necessity,” adding that it is “not possible to say that the outer islands are required for the defence purposes” of Britain and the United States. He did, however, warn that settlers must secure the necessary permits to live there permanently.

The ruling poses a threat to the U.K.-Mauritius deal signed in 2024, whereby Britain agreed to transfer sovereignty of the Chagos Islands to Mauritius and lease Diego Garcia for 99 years for around $4.5 billion. The deal restricted resettlement to Diego Garcia, but the judge determined that the United........

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