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Formerly administered as part of the British Crown Colony of Mauritius, the British Indian Ocean Territory (BIOT) was established as an overseas territory of the UK in 1965. A number of the islands in the territory were later transferred to the Seychelles when it gained independence in 1976. Subsequently, BIOT has consisted of the six main island groups that make up the Chagos Archipelago. Only Diego Garcia, the largest and most southerly of the islands, is inhabited. It contains a joint UK-US naval support facility and hosts one of four dedicated ground antennas that assist in the operation of the Global Positioning System (GPS) navigation system -- the others are on Kwajalein (Marshall Islands); at Cape Canaveral, Florida (US); and on Ascension Island (Saint Helena, Ascension, and Tristan da Cunha). The US Air Force also operates a telescope array on Diego Garcia as part of the Ground-Based Electro-Optical Deep Space Surveillance System (GEODSS) for tracking orbital debris, which can be a hazard to spacecraft and astronauts. <br><br>Between 1967 and 1973, the former agricultural workers who lived on the islands were relocated, primarily to Mauritius but also to the Seychelles. Negotiations with the UK between 1971 and 1982 resulted in the establishment of a trust fund to compensate the displaced islanders, known as Chagossians. Beginning in 1998, the islanders pursued a series of lawsuits against the British Government, seeking further compensation and the right to return to the territory. British court rulings in 2006 and 2007 invalidated immigration policies that had excluded the islanders from the archipelago, but in 2008, the House of Lords -- the final court of appeal in the UK -- ruled in favor of the British Government by overturning the lower court rulings and finding no right of return for the Chagossians. In 2015, the Permanent Court of Arbitration unanimously held that the marine protected area that the UK declared around the Chagos Archipelago in 2010 violated the UN Convention on the Law of the Sea.<br><br>In 2019, the International Court of Justice ruled in an advisory opinion that Britain’s decolonization of Mauritius was not lawful because of continued Chagossian claims. A non-binding 2019 UN General Assembly vote demanded that Britain end its “colonial administration” of the Chagos Archipelago and that it be returned to Mauritius. On 22 May 2025, the United Kingdom and Mauritius signed an agreement that will lead to the transfer of sovereignty of the Chagos Archipelago to Mauritius. Under the agreement, the United Kingdom will lease Diego Garcia from Mauritius for 99 years and maintain full operational control of the joint UK-US military base.

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archipelago in the Indian Ocean, south of India, about halfway between Africa and Indonesia

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6 00 S, 71 30 E

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<strong>note:</strong> Diego Garcia 7 20 S, 72 25 E

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Political Map of the World

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<strong>note:</strong> includes the entire Chagos Archipelago of 55 islands

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land area is about one-third the size of Washington, D.C.

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698 km

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tropical marine; hot, humid, moderated by trade winds

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flat and low coral atolls (most areas do not exceed 2 m, or 6.6 ft, in elevation); sits atop the submarine volcanic Chagos-Laccadive Ridge

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coconuts, fish, sugarcane

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none; located outside routes of Indian Ocean cyclones

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<p><strong>note 1:</strong> archipelago of 55 islands; Diego Garcia, the largest and southernmost island, occupies a strategic location in the central Indian Ocean</p> <p><strong>note 2:</strong> Diego Garcia is the only inhabited island of the BIOT</p>

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<strong>note:</strong> Diego Garcia, the largest of the 58 islands, hosts a joint UK-US military facility 

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wastewater discharge into the lagoon on Diego Garcia

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tropical marine; hot, humid, moderated by trade winds

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overseas territory of the UK; administered by a commissioner, resident in the Foreign, Commonwealth, and Development Office in London

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the laws of the UK apply&nbsp;

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none (overseas territory of the UK)

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UPU

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<strong>description:</strong> white with six wavy blue horizontal stripes; the UK flag is in the upper-left quadrant; the striped section has a palm tree and yellow crown (the territory's symbols) centered on the right half of the flag<br><br><strong>meaning:</strong> the wavy stripes represent the Indian Ocean; the six blue stripes may stand for the six main atolls of the archipelago

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small island territory economy; economic activity mainly on Diego Garcia with national military installations; recently settled disputes with Mauritius have increased oil exports; established marine reserve has limited commercial fishing

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Singapore 86%, Pakistan 8%, USA 1%, South Africa 1%, Czechia 1% (2023)

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<b>note:</b> top five export partners based on percentage share of exports

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fish (2023)

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<strong>note:</strong> top export commodities based on value in dollars over $500,000

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Greece 52%, Singapore 38%, USA 4%, Panama 2%, UAE 2% (2023)

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<b>note:</b> top five import partners based on percentage share of imports

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refined petroleum, animal products, aluminum structures, insulated wire, prefabricated buildings (2023)

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<b>note:</b> top five import commodities based on value in dollars

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<p>the US dollar is used</p>

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Armed Forces Radio and Television Service (AFRTS) broadcasts over 3 frequencies for US and UK military personnel stationed on the islands

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.io

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Diego Garcia hosts one of four dedicated ground antennas that assist in the operation of the Global Positioning System (GPS) navigation system (the others are on Kwajalein (Marshall Islands), at Cape Canaveral, Florida (US), and on Ascension Island (Saint Helena, Ascension, and Tristan da Cunha))

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1 (2025)

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no regular military forces

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defense is the responsibility of the UK; on 22 May 2025, the United Kingdom and Mauritius signed an agreement that will lead to the transfer of sovereignty of the Chagos Archipelago to Mauritius;&nbsp;under the agreement, the United Kingdom will lease Diego Garcia from Mauritius for 99 years and maintain full operational control of the joint UK-US military base