British Indian Ocean Territory

The British Indian Ocean Territory (BIOT) is a British Overseas Territory located in the Indian Ocean. It consists of the seven atolls of the Chagos Archipelago, which include over 1,000 small islands covering 60 square kilometres (23 square miles). The largest island is Diego Garcia, where a important Joint Military Facility is shared by the United Kingdom and the United States.

The area has been the subject of disagreement between the United Kingdom and Mauritius. Mauritius believes the islands were unfairly separated from it, while the UK disagrees. In the late 1960s and early 1970s, about 2,000 people who lived there were moved away to make way for the military base. These people, known as Chagossians, have long hoped to return home.

In 2026, six Chagossians tried to settle on one of the islands, Île du Coin, but their effort is facing legal challenges. Recently, discussions have taken place about eventually giving control of the islands to Mauritius while keeping the military base on Diego Garcia. However, these plans are currently not moving forward due to concerns raised by the government of the United States.

History

Maldivian mariners knew of the Chagos Islands, called Fōlhavahi and Hollhavai. Sometimes traders and fishermen would get lost and end up on these islands before being rescued. The islands were too far from Maldives to settle permanently, so they were ignored for centuries.

Views of the Chagos Archipelago from lieutenant Archibald Blair, 1787.

The islands were first charted by Vasco da Gama in the early 1500s and later claimed by France in the 1700s. They were settled by African slaves and Indian workers who built coconut plantations. In 1810, Mauritius was captured by the United Kingdom, and France gave up the islands in 1814.

The United Kingdom ended slavery in 1833, but people on the islands continued working. In 1962, a new company bought the plantations. An airstrip was built on Diego Garcia during the Second World War for military use, but the military left after the war ended.

Nautical chart of the Chagos Archipelago from captain of the East India Company's Indian Navy Robert Moresby, 1837.

In 1965, the United Kingdom split the Chagos Archipelago from Mauritius to create the British Indian Ocean Territory, mainly to build a military base with the United States. The local population of about 2,000 people, known as Chagossians, were moved away from the islands between 1967 and 1973 so the base could be built.

Work on the military base began in 1971, and it has been used by both the UK and US ever since. The islands of Aldabra, Farquhar, and Desroches were returned to Seychelles in 1976.

Mauritius has claimed the islands should belong to them, arguing the separation in 1965 was unfair. Legal battles over this have continued for years. In 2019, an international court said the UK should give the islands back to Mauritius, but the UK did not accept this decision.

In February 2026, four Chagossians tried to settle on one of the islands, Île du Coin, but were stopped by a court order.

Responses to transfer of BIOT

In July 2025, a legal case began where the British government was asked to talk with the Chagossians before deciding what to do with their land. The court agreed to look at the case quickly, but by February 2026, the judge had not shared the decision.

In June 2025, Chagossian activists sent a legal request to the United Nations Human Rights Committee. They said the deal between the UK and Mauritius was unfair because it was made without asking the Chagossians.

In December 2025, some Chagossians who did not want to give up their land to Mauritius set up a government in exile. After they moved back to their old town, Île du Coin, in February 2026, they changed the name to remove "in-exile".

In the House of Lords, members said the deal about the Chagos Islands was not perfect but needed to be approved. They said the government could not ignore the risk of losing the right to use the military base.

In June 2025, a group started a legal case saying the British government acted illegally when signing the agreement with Mauritius. Later, the British Conservative Party suggested not to approve the agreement made on May 22, 2025.

In February 2026, the UK Secretary of State for Defence, John Healey, was accused of giving wrong information to Parliament. He had said that if the UK did not give the British Indian Ocean Territory to Mauritius, they could lose legal cases quickly and the base at Diego Garcia might stop working. However, there is a rule that protects military activities from these legal cases.

The Prime Minister of Mauritius, Navin Ramgoolam, praised the agreement, calling it a win for fairness and for the Chagossian people. But it still needed approval from the UK Parliament.

The United States welcomed the agreement because it helps keep the joint US-UK military base at Diego Garcia working. However, in January 2026, US President Donald Trump called the agreement a mistake, saying it showed weakness. In February 2026, he posted again saying the UK should not give away Diego Garcia.

The United Nations said the agreement was an important step in solving a long dispute in the Indian Ocean region. Some UN experts, however, said the agreement did not protect the rights of the Chagossian people and asked for it to be renegotiated.

India also welcomed the agreement, seeing it as a move towards finishing the process of decolonising the island nation, following international law.

Government

Main articles: Government of the British Indian Ocean Territory and Commissioner for the British Indian Ocean Territory

The British Indian Ocean Territory is a part of the United Kingdom, and King Charles III is the head of state. There is no governor because there are no permanent people living there. The main leader is called the Commissioner, and Nishi Dholakia is the current one.

King Charles III is the head of state of the British Indian Ocean Territory.

The laws come from a special rule book made in 2004. Since there are no permanent people, there are no elections or a local government. Most of the people living there are part of the United States military, so any problems are usually handled by their military rules.

Chagossian Government

Main article: Chagossian Government

The Chagossian Government claims to speak for the Chagossian people of the British Indian Ocean Territory. It started in December 2025 and was called the Chagossian Government-in-Exile. In February 2026, it changed its name after its leader Misley Mandarin returned to the islands.

Naval Party 1002 and MV Grampian Frontier

Naval Party 1002 (NP 1002) is based in the British Indian Ocean Territory. It includes members from the Royal Navy and Royal Marines. Their job is to help with the territory's administration and keep things safe. They also handle customs and security tasks.

Before 2017, a ship called MV Pacific Marlin was used for patrols around the territory. In 2016, a new ship called MV Grampian Frontier started working there. This ship is 70 metres long and can carry up to 24 people. It helps with patrols, research, and conservation work. Sometimes, it works with NP 1002 members on these tasks. In 2022, it helped a ship bring some people back to Blenheim Reef.

The Royal Navy also has two ships, HMS Tamar and HMS Spey, that can visit the area to help protect the territory and do other important jobs. HMS Tamar visited in early 2023 to help with fishing rules and other tasks.

Geography

Main article: Geography of the British Indian Ocean Territory

The British Indian Ocean Territory is a group of islands in the Indian Ocean. It has 58 islands that cover 56 square kilometres (22 square miles). The biggest island is Diego Garcia, which is 32.5 square kilometres (12.5 square miles) and makes up about half of the land. The other islands are much smaller. The land is flat and low, with an average height of just 1.33 metres (4.4 feet) above sea level. In 2010, a large area of ocean around the islands became a marine reserve.

The islands are:

These islands are located between 4°44 and 7°41 south and 70°47 and 72°47 east.

The airport passenger terminal in Diego Garcia, complete with red British telephone box.

Climate

The climate is tropical marine; hot and humid, with winds from the southeast from May to November. The average temperature is 27 °C (81 °F). Rain is common, and the islands are safe from strong storms that affect areas further south. The military base on Diego Garcia is one of the U.S. military's bases most affected by climate change.

Transport

Salomons Atoll

On Diego Garcia, there are short paved roads between the port and the airfield. Most people walk or ride bicycles. The island used to have small railways pulled by donkeys, but they are no longer used. Diego Garcia's military base has the territory's only airport. The runway is long enough for big planes, including U.S. bombers. There is also a big naval port. Boats can get permits to stay near the outer islands, but they must stay far away from certain protected areas. Only authorised people can go to Diego Garcia, and boats cannot come close to the island.

Unlike other British territories, BIOT drives on the right side of the road because it follows U.S. traffic rules.

Conservation

The territory is part of the International Whaling Commission's 1979 Indian Ocean Whale Sanctuary. In 1998, it joined the Ramsar Convention, and steps were taken to protect non-military areas of Diego Garcia. The territory also follows rules to protect wildlife and the environment.

On 1 April 2010, a large marine protected area was created around the islands. This doubled the world's protected ocean areas. It helps scientists study climate change and marine life, and it serves as a safe place for animals that are in danger elsewhere. Fishing is not allowed in this area.

The British Indian Ocean Territory has helped some people from the Chagossian community visit the islands and take part in scientific work. The waters around the islands are rich for fishing, but illegal fishing has been a problem. The Royal Navy has helped monitor the area to protect it.

Demographics

The British Indian Ocean Territory has special rules. The government says people cannot live there permanently because the land is used for defense by the Government of the United Kingdom and the Government of the United States of America. Only Diego Garcia, the largest island, has people living there. Most of these people are military staff or workers, and families are not allowed to live on the island. Schools are not available there.

In 2021, a group of people from Sri Lanka, including children, ended up on Diego Garcia after their boat had problems. They were kept in a fenced area and were not allowed to leave without guards. There were concerns about their safety and treatment. In 2026, some people whose families were moved from the islands in 1971 tried to return to live there, but they were told to leave. A court stopped them from being forced away for a short time.

Economy

All economic activity happens on Diego Garcia, where joint UK/US defence facilities are located. People from Britain, Mauritius, the Philippines, and the United States work there to build and run services for the military. There are no factories or farms on the islands. In the past, allowing commercial fishing brought in about US$1 million each year.

United States President Donald Trump announced a 10% tariff on the British Indian Ocean Territory on 2 April 2025.

Services

The Navy Morale, Welfare and Recreation section offers places like a library, an outdoor cinema, shops, and sports centres on Diego Garcia, with prices in US dollars. The BIOT Post Office handles mail, and the territory has issued stamps since 17 January 1968. Originally, these stamps used rupees, but after 1992, they used pound sterling, the territory's official money. Basic health services are available, and people can be taken far away for more serious medical care. The territory does not have schools.

Telecommunications

Cable & Wireless began providing phone and internet services in 1982. In April 2013, the company was bought by the Batelco Group and renamed Sure (Diego Garcia) Ltd.

Because Diego Garcia is close to the Equator, it can see many geosynchronous satellites. The island has a special station called Diego Garcia Station (DGS) that helps track satellites for the United States Space Force.

In spring 2022, Diego Garcia was linked to a fast underwater submarine communications cable as part of a new cable connecting Perth to Muscat. This cable also connects to Australia's Cocos Islands, which has an airfield. The cable cost $300 million, and the U.S. Department of Defense paid about a third of that.

Broadcasting

The territory has three FM radio stations run by the American Forces Network and British Forces Broadcasting Service (BFBS). People can also use amateur radio from Diego Garcia with the British callsign prefix VQ9.