How a strategic military base led to the detachment of the Chagos Archipelago
In short: In 1965, the United Kingdom separated the Chagos Archipelago from Mauritius to facilitate a joint military base with the United States on Diego Garcia. This move triggered decades of international legal disputes, forced removals, and a landmark ruling that the UK must end its administration of the islands.
The Chagos Archipelago, historically administered by the UK as a dependency of Mauritius, became the subject of intense geopolitical maneuvering in the 1960s. Following joint surveys in 1964, the UK and the U.S. identified Diego Garcia as a prime location for a military facility. To secure the land, the UK detached the archipelago from Mauritius in November 1965, a decision that forced the removal of the entire local population between 1967 and 1973.
Mauritius consistently challenged this separation, arguing it violated UN resolutions against the dismemberment of colonial territories. Legal pressure mounted over the years, culminating in a 2019 advisory opinion from the International Court of Justice. The court ruled that the detachment was not based on a free expression of the people and that the UK was under an obligation to end its administration as rapidly as possible. This was supported by a 2015 Permanent Court of Arbitration ruling, which found that the UK's creation of a marine protected area around the islands in 2010 violated international law.
The path to resolution has been complex and controversial. In October 2024, the UK agreed to hand over the islands to Mauritius, a deal signed in May 2025. However, the agreement faced significant political headwinds, including criticism from U.S. President Donald Trump, who labeled the deal an act of great stupidity. By April 2026, the ratification process was stalled, reflecting the enduring tension between sovereign rights, international legal obligations, and the strategic importance of military infrastructure in the Indian Ocean.
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- Summary by Intellect · source: Chagos Archipelago sovereignty dispute
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