In the middle of the Indian Ocean lies Diego Garcia, a remote atoll that has become one of the most important military bases on Earth. Long before it had its own runways, warships and military operations, the island was home to an entire community, the Chagosans, whose ancestors have lived across the Chagos Archipelago for generations.
Between 1967 and 1973, the United Kingdom and the United States forcibly evacuated the entire population of the islands to make way for a joint military base, a decision that decades of legal battles, human rights findings and international court rulings have since described as a serious violation of international law. Human rights groups continue to push for Chagos residents to have direct input into resettlement plans, arguing that a community they displaced without their consent decades ago deserves real consultation now rather than having decisions made again on their behalf.
How the complete depopulation deal was reached
According to the ICJ’s summary of its 2019 advisory opinion, the United States approached the United Kingdom in 1964 to express interest in establishing a military base on Diego Garcia, and the two governments subsequently agreed to completely depopulate the archipelago to pave the way for it. The court found that between 1967 and 1973, the United Kingdom prevented Chagossians from returning to the islands or forcibly evacuated them, with the main forced transfer from Diego Garcia itself occurring in July and September 1971.
According to a detailed report by Human Rights Watch, the UK falsely declared to the UN that the Chagos Archipelago had no permanent population, allowing it to avoid officially reporting its colonial administration of the islands even as an entire indigenous community was displaced.
A community uprooted without warning
The scale of displacement was large for such a small population. Approximately 1,500 to 2,000 Chagosans were removed from the archipelago, primarily relocated to Mauritius and the Seychelles, often with little preparation for the sudden loss of their homeland.
Human Rights Watch has documented first-hand accounts from Chagos residents describing their sudden realization that they would never be allowed to return, with one island resident, Louis Marcel Humbert, recalling his mother’s words after the family left on what was supposed to be a temporary trip to Mauritius in 1967, where they now had to live a very different life.
A legal battle spanning five decades
The Chagossians’ fight to return to their homeland has continued through the UK courts for decades. In 2008, the British House of Lords, then the country’s highest court, overturned previous Supreme Court and Court of Appeal rulings that granted islanders the right to return, and an immigration order first issued in 1971 continued to prevent them from returning. The dispute eventually reached international bodies, culminating in a 2019 ICJ advisory opinion, which by a vote of thirteen judges to one found that the UK’s separation of the Chagos Archipelago from Mauritius in 1965 was unlawful, and called on the UK to end its administration of the islands as soon as possible.
Why did the UK initially resist international rulings?
Despite the ICJ’s findings, the UK government initially insisted that the ruling was merely advisory and not legally binding, and continued to administer the territory. According to Human Rights Watch, the UK effectively ignored the 2019 ruling until November 2022, when it finally entered into formal negotiations with Mauritius over the future of the islands. A separate ruling by the UN International Tribunal for the Law of the Sea in 2021 confirmed that the UK had no valid claim to sovereignty over the islands, increasing international pressure on London to resolve the dispute.
The 2025 treaty that finally resolved the issue of sovereignty
According to the UK House of Commons Library’s official briefing on the agreement, the UK and Mauritius signed a treaty on 22 May 2025 under which the UK agreed to cede full sovereignty of the Chagos Archipelago to Mauritius, while ensuring the UK and US continued rights to operate the military base at Diego Garcia. Under the terms of the deal, the UK will lease back Diego Garcia for an initial period of 99 years, with the House of Lords Library noting that the agreement also includes security and financial provisions, including an annual payment from the UK to Mauritius.
Mauritius will be free to pursue resettlement in the rest of the Chagos Archipelago, but not in Diego Garcia itself, where the military base will continue to operate.
Why does Diego Garcia remain of such great strategic importance?
Diego Garcia’s importance to the United States and the United Kingdom stems from its location approximately halfway between Africa and Indonesia in the Indian Ocean, making it a valuable staging point for military operations throughout the region. The base served as a staging ground for bombing campaigns during the conflicts in Iraq and Afghanistan, and continues to support surveillance and rapid deployment capabilities across the Indo-Pacific region.
This strategic value is precisely why both governments are moving to ensure that the base continues to operate for decades to come, even as the UK formally surrenders its sovereignty over the wider archipelago.
What does the 2025 agreement mean, and what does it not mean, for the Chagossians themselves?
While the treaty resolves the long-standing sovereignty dispute between the United Kingdom and Mauritius, it does not fully resolve the concerns of the Chagossian community itself. According to Human Rights Watch, several Chagossians interviewed said they had not been properly consulted before the 2025 agreement was announced, and while most said they personally would like to return to the islands, they did not seek to close the military base itself, hoping instead to live alongside it on Diego Garcia as well as other habitable islands in the archipelago.
More than fifty years after their displacement, the Chagossians’ right to return to Diego Garcia specifically remains unresolved, even as sovereignty over the broader archipelago has finally been transferred.
