The British Indian Ocean Territory (BIOT) is a British overseas territory of the United Kingdom situated in the Indian Ocean halfway between Tanzania and Indonesia. The territory comprises the seven atolls of the Chagos Archipelago with over 1,000 individual islands – many very small – amounting to a total land area of 60 square kilometres. The largest and most southerly island is Diego Garcia, 27 km, the site of a joint military facility of the United Kingdom and the United States.
The only inhabitants are US and British military personnel and associated contractors, who collectively number around 3,000 (2018 figures). The forced removal of Chagossians from the Chagos Archipelago occurred between 1968 and 1973. The Chagossians, then numbering about 2,000 people, were expelled by the British government to Mauritius and Seychelles to allow the United States to build a joint UK–US military base there. Today, the exiled Chagossians are still trying to return, pointing out that the forced expulsion and dispossession was illegal, but the British government has repeatedly denied them the right of return. The islands are off-limits to Chagossians, casual tourists, and the media.
Since the 1980s, the Government of Mauritius has sought to regain control over the Chagos Archipelago, which was separated from the then British Colony of Mauritius by the UK in 1965 to form the British Indian Ocean Territory. On 22 May 2019, the United Nations General Assembly (UNGA) adopted a resolution, affirming that "the Chagos Archipelago forms an integral part of the territory of Mauritius", citing the February 2019 advisory opinion of the International Court of Justice (ICJ) on the separation of the archipelago from Mauritius. The motion was approved by a majority vote with 116 member states voting for and 6 against.
The British Indian Ocean Territory is one of only two British territories where traffic drives on the right, the other being Gibraltar.