Sovereignty of the Chagos Archipelago

 

 

Critics have warned that the treaty could threaten the UK-US military base on Diego Garcia and enable China to expand its power in the Indian Ocean © Alamy

 

Salomon Atoll is one of the many above water features of the Chagos Archipelago

 

Abandoned church on Boddam Island, Salomon Atoll

 

 

The Chagos Archipelago (/ˈtʃɑːɡəs, -ɡoʊs/) or Chagos Islands (formerly the Bassas de Chagas,  and later the Oil Islands) is a group of seven atolls comprising more than 60 islands in the Indian Ocean about 500 kilometres (310 mi) south of the Maldives archipelago. This chain of islands is the southernmost archipelago of the Chagos–Laccadive Ridge, a long submarine mountain range in the Indian Ocean.  In its north are the Salomon Islands, Nelsons Island and Peros Banhos; towards its south-west are the Three Brothers, Eagle Islands, Egmont Islands and Danger Island; southeast of these is Diego Garcia, by far the largest island. All are low-lying atolls, save for a few extremely small instances, set around lagoons.

 

The Chagos Islands had been home to the Chagossians, a Bourbonnais Creole-speaking people, until the United Kingdom expelled them from the archipelago at the request of the United States between 1967 and 1973 to allow the United States to build Naval Support Facility Diego Garcia, a military base on Diego Garcia, on land leased from the UK military in the British Indian Ocean Territories.

 

B-2 bomber take off, B-52 bombers on tarmac on Diego Garcia in 2003

 

 

Since 1971, only the atoll of Diego Garcia has been inhabited, and only by employees of the US military, including American civilian contracted personnel. Since being expelled, Chagossians, like all others not permitted by the UK or US governments, have been prevented from entering the islands.

 

From 1715 to 1810, the Chagos Islands were part of France's Indian Ocean possessions, administered through Isle de France - which was a colony of France (later renamed as Mauritius). Under the Treaty of Paris (1814), France ceded Isle de France and the Chagos Islands to the United Kingdom.

 

In 1965, the United Kingdom split the Chagos Archipelago away from Mauritius, and the islands of Aldabra, Farquhar, and Desroches from the Seychelles, to form the British Indian Ocean Territory. The islands were formally established as an overseas territory of the United Kingdom on 8 November 1965.

 

 During UK-US discussions on the Indian Ocean in November 1975, the United Kingdom expressed its intention to return the islands of Aldabra, Farquhar, and Desroches to Seychelles to facilitate its peaceful transition to independence by June 1976.

 

 Both the UK and the United States acknowledged that these islands could not be used for defense purposes, as they were populated, and forcibly removing inhabitants, as had occurred in the Chagos Archipelago, would be politically unfeasible.  

 

The Chagos Archipelago. (Atolls with areas of dry land are named in green)

Major islands :   Diego Garcia, Peros Banhos, Salomon Islands, Egmont Islands

Ethnic groups  : 95.88% British / American,  4.12% others,   (native population exiled)

 

 

On 18 March 1976, the UK and Seychelles signed an agreement to transfer the islands, which officially returned to Seychelles on its Independence Day, 29 June 1976.  

The British Indian Ocean Territory now comprises the Chagos Archipelago only.

 

Between 1967 and 1973, the entire population of the Chagos Archipelago was either prevented from returning or forcibly removed by the United Kingdom. The main forcible removal of Diego Garcia’s population took place in July and September 1971.

Mauritius has since been engaged in a sovereignty dispute with the UK, claiming the Chagos Archipelago as part of Mauritius.

 

In 2004, the UK amended its exclusion clause to block Mauritius from taking the Chagos dispute to the International Court of Justice. This move ensured that even if Mauritius left the Commonwealth, it could not challenge the UK in court.

 

On 18 March 2015, the Permanent Court of Arbitration ruled that the UK's marine protected area around the Chagos Archipelago violated international law. The tribunal upheld Mauritius' sovereignty claims, rejecting the UK's argument and affirming its binding commitments on fishing and mineral rights.

 

On 23 June 2017, the UN General Assembly voted to refer the Chagos dispute to the International Court of Justice, which began hearings in 2018. While 17 countries backed Mauritius, the UK insisted the issue should be resolved through bilateral talks.

 

In 2019, the International Court of Justice (ICJ) issued a non-binding advisory opinion stating that the UK "has an obligation to bring to an end its administration of the Chagos Archipelago as rapidly as possible, and that all Member States must co-operate with the United Nations to complete the decolonization of Mauritius".

 

In 2021, the International Tribunal for the Law of the Sea confirmed for its jurisdiction, in a binding ruling, that the UK has "no sovereignty over the Chagos Islands", and thus the islands should be handed back to Mauritius.

 

In August 2021, the Universal Postal Union banned BIOT stamps from being used in the BIOT, a move Mauritian Prime Minister Pravind Jugnauth called a "big step in favour of the recognition of the sovereignty of Mauritius over the Chagos".

 

In October 2024, the British government announced it would hand over sovereignty of the Chagos Islands to Mauritius subject to finalisation of a treaty.  The Chagossian people living in the UK have criticised the deal for not having included the Chagossian community in the decision-making process.  A segment of the Chagossian community, particularly those with British citizenship residing in the UK, favor continued British sovereignty over the Chagos Archipelago, expressing concerns that their interests may not be fully safeguarded under Mauritian administration.

 

However, many Chagossians, including those in Mauritius, support Mauritian sovereignty. The Chagos Refugees Group, the largest Chagossian advocacy organization, has been a leading voice for this position. Its leader, Olivier Bancoult, described the UK's decision to return the Chagos Archipelago to Mauritius and allow Chagossians to resettle on the outer islands as a significant step and an acknowledgment of past injustices.

 

The deal was put on hold following the 2024 United States presidential election to allow consideration from the new incoming administration.

 

On 27 February 2025, speaking in the Oval Office alongside Prime Minister Sir Keir Starmer, U.S. President Donald Trump stated that he was willing to support the agreement to transfer sovereignty of the Chagos Islands to Mauritius

 

People and language

 

Chagossians

 

The islanders were known as the Ilois (a French Creole word for "islanders") and they numbered about 1,000. They were of mixed African, South Indian, Portuguese, English, French and Malay descent and lived very simple, spartan lives in their isolated archipelago working in the coconut and sugar plantations, or in the fishing and small textile industries. Few remains of their culture have been left, although their language is still spoken by some of their descendants in Mauritius.

 

The inhabitants of Chagos were speaking Chagossian Creole, also known as Ilois creole, a French Creole which has not been properly researched from the linguistic point of view.

 

A Chagossian photographed by a US National Geodetic Survey team in 1971

An unnamed Diego Garcian at the time of the US encampment, 1971. Location: Chagos, Diego Garcia Island 

 

 

The island names are a mixture of Dutch, French, English and Ilois Creole.

The Ilois who inhabited the islands were forcibly removed by the US and British governments during the late 1960s and early 1970s—effectively turning the islands into a military base. While a number of islanders had petitioned for the return of their former homes and their right to return has been recognised by the UN General Assembly, the International Court of Justice, and the International Tribunal for the Law of the Sea, the US and UK legal systems have refused to adhere to these decisions, leaving the Chagossians in exile.

 

Other

 

Diego Garcia is currently the only inhabited island in the Chagos, all of which compose the British Indian Ocean Territory, usually abbreviated as "BIOT". The UK considers it an Overseas territory of the United Kingdom, and the Government of the BIOT consists of a Commissioner appointed by the King on the advice of the Foreign and Commonwealth Office.

 

The Commissioner is assisted by an Administrator and small staff, and is based in London and resident in the Foreign and Commonwealth Office. This administration is represented in the Territory by the Officer commanding British Forces on Diego Garcia, the "Brit Rep". Laws and regulations are promulgated by the Commissioner and enforced in the BIOT by the British Representative.

 

There are no indigenous peoples living on the island, and the UK represents the Territory internationally. A local government as normally envisioned does not exist.  Around 1,700 armed services personnel and 1,500 civilian contractors, mostly American, are stationed on Diego Garcia.

 

As of 2012, the islands have a transitory population of about 3,000 including 300 British government personnel, 2,700 United States Army, Navy and Air Force personnel.

 

The Catholics are pastorally served by the Roman Catholic Diocese of Port-Louis, which includes the BIOT.

 

The brain coral Ctenella chagius is endemic to the reefs of the Chagos

 

Ctenella is a monotypic genus of stony coral in the family Euphylliidae. It is represented by a single species, Ctenella chagius. These corals are massive in size with meandering valleys between the calyces which have solid, non-porous walls and fine, evenly spaced, solid septae. They are found in the Indian Ocean being endemic to the Chagos Archipelago. It forms solid, smooth hemispherical domes.

 

Ctenella는 Euphylliidae과에 속하는 돌산호의 단일형 속입니다. 단일종인 Ctenella chagius로 대표됩니다. 이 산호는 크기가 거대하며, 단단하고 다공성이 없는 벽과 가늘고 균등하게 간격을 두고 있는 단단한 격벽을 가진 꽃받침 사이에 구불구불한 계곡이 있습니다. 그들은 차고스 군도의 고유종인 인도양에서 발견됩니다. 단단하고 매끄러운 반구형 돔을 형성합니다.

 

돌산호목Madreporaria

보통 돌산호(stony corals)나 진정산호(true corals)라고 하는데, 열대수역의 천해에 다양한 종이 풍부하게 발달해 산호초 형성에 주역을 맡고 있어 조초산호라고도 한다. 단체 또는 군체로서 단단한 바닥 위에 고착하고, 천해에서 심해까지 분포한다.

자웅동체로, 성숙한 알과 정자는 수정하여 플라눌라(planula)가 되며, 착생한 다음 폴립으로 변태하고 골격을 분비하면서 자란다. 폴립은 출아법을 통해 무성생식으로 증식하여, 각 종 특유의 커다란 군체를 이룬다. 내부 구조는 말미잘과 비슷하나 말미잘과 달리 석회질 골격이 발달되어 있다. 촉수는 깃 모양이 아니며 단순하고, 격막은 6의 배수로 오래된 격막 사이에서 생겨나며, 견인근이 발달하여 골격 속으로 퇴축할 수 있다. 흰색 골격 표면을 얇은 조직이 덮고 있어 살아 있을 때는 아름다운 색을 나타낸다.

화석은 트라이아스기 중엽부터 나타나며, 우리나라에는 현재 24종이 분포한다.

 

Table coral of genus Acropora (Acroporidae) at French Frigate Shoals, Northwestern Hawaiian Islands

 

 

Seabirds nesting on South Brother island in the Chagos Archipelago

 

Coconut crabs are the world's largest terrestrial arthropod and live in one of the most undisturbed populations

in the Chagos

 

 

Diego Garcia

 

The key Diego Garcia base is in the Chagos Islands in the Indian Ocean 

 

Diego Garcia

 

 

B-2 Spirit

 

There is a joint UK-US military base on Diego Garcia, one of a cluster of islands

in the Indian Ocean known as the Chagos Islands 

(US Department of Defense/PA)