Diego Garcia

Diego Garcia is an atoll located in the heart of the Indian Ocean, some 1,000 miles (1,600 km) south off India's and Sri Lanka's southern coast. Diego Garcia is the largest atoll by land area of the Chagos Archipelago. It is part of the British Indian Ocean Territory (BIOT), a British overseas territory.

Since the enforced depopulation of Diego Garcia in the years leading up to 1973, it has been used as a military base by the United States and the United Kingdom. Diego Garcia hosts one of three ground antennas (others are on Kwajalein and Ascension Island) that assist in the operation of the Global Positioning System (GPS) navigational system.

The atoll is now covered in luxuriant tropical vegetation, with little sign left of the copra and coconut plantations that once covered it. The island is 37 miles (60 km) long, with a maximum elevation of 22 feet (7 m), and nearly encloses a lagoon some 12 miles long (19 km) and up to 5 miles (8 km) wide. Depths in the lagoon extend to 98 feet (30 m), while numerous coral heads extend toward the surface and form hazards to navigation. Shallow reefs surround the island on the ocean side as well as within the lagoon. The channel and anchorage area are dredged, while the old turning basin can also be used if its depth is sufficient for the ship.


The atoll forms a nearly complete rim of land around a lagoon, following 90 percent of its perimeter, with an opening only in the North. The main island is the largest of some sixty islands which form the Chagos Archipelago. Besides the main islands, there are three small islets at the mouth of the lagoon in the north:

  • West Island (8.4 acres/3.4 ha)
  • Middle Island (14.8 acres/6 ha)
  • East Island (29 acres/11.75 ha)

The total area of the atoll measures 66 square miles (170 km², or 174 km², of which 12 square miles (30 km²) are land area, 6.5 square miles (17 km²) peripheral reef and 48 square miles(124 km²) are lagoon.


Annual rainfall averages 102 inches (260 cm) with the heaviest precipitation occurring from October to February, though even the driest month (August) averages 4.2 inches (10 cm). Temperatures are generally close to 30 °C (high 80s Fahrenheit) by day, falling to the low 20s °C (70°F) by night. Humidity is high throughout the year. However the almost constant breezes keep conditions reasonably comfortable.

Diego Garcia is at risk from tropical cyclones. The surrounding topography is low and does not provide an extensive wind break. However since the 1960s, the island has not been seriously affected by a severe tropical cyclone, even though it has often been threatened. The maximum sustained wind associated with a tropical cyclone in the period 1970-2000 at Diego Garcia has been approximately 40 knots (75 km/h).

The island was somewhat affected by the tsunami caused by the 2004 Indian Ocean earthquake. Service personnel on the western arm of the atoll island reported only a minor increase in wave activity. The island was protected to a large degree by its favorable ocean topography. About 50 miles (80 km) east of the atoll lies the 400-mile (650 km) long Chagos Trench, an underwater canyon plunging more than 16,000 feet (4,900 m). The depth of the trench and its grade to the atoll's slope and shelf shore makes it more difficult for substantial tsunami waves to build before passing the atoll from the east. In addition, near shore coral reefs and an algal platform may have dissipated much of the waves' impact. A biological survey conducted in early 2005 indicated erosional effects of the tsunami wave on Diego Garcia and other islands of the Chagos Archipelago. One stretch of shoreline on the eastern side of the atoll 200 to 300 meters long (about 650 to 1000 feet long) was verified to have been breeched and inundated by the tsunami wave. That is about 10% of the eastern arm of the atoll. The biological survey reports that in addition to coastal erosion, shoreline shrubs and small to medium size coconut palms were washed away along the stretch where the wave broke through. (See the April 2005 edition of the Chagos News no.25 for more information and photos [http://www.chagosconservationtrust.org/Chagos%20News/News25.pdf].)

On November 30, 1983 a magnitude 7 earthquake 34 miles (55 km) northwest of the island spawned a small tsunami resulting in a 5-foot (1.5 m) rise in wave height in the Diego Garcia lagoon, causing some damage to buildings, piers and the runway.


Portuguese explorers discovered Diego Garcia in the early 16th century. The island's name is believed to have come from either the ship's captain or the navigator on that early voyage of discovery.

The islands remained uninhabited until the 18th century when the French established copra plantations with the help of slave labor. Diego Garcia became a possession of the United Kingdom after the Napoleonic wars, and from 1814 to 1965, it was a dependency of Mauritius.

In 1965, the Chagos Islands, which include Diego Garcia, were detached from Mauritius to form part of the British Indian Ocean Territories (BIOT). In 1966, the crown bought the islands and plantations, which had been under private ownership and which had not been profitable with the introduction of new oils and lubricants. In 1971, the plantations were closed because of the agreement between the United Kingdom and the United States to make Diego Garcia available to the U.S. as a military base. No payment was made as part of this arrangement, although it has been claimed that the United Kingdom received a US$14 million discount on the acquisition of Polaris missiles from the United States. This agreement also forbids any other economic activity on the island.

Until 1971, Diego Garcia had a native population, known as the Chagossians (or Ilois), which was composed of the descendants of East Indian workers and African slaves who had been brought to the island in the eighteenth and nineteenth centuries to work on the coconut and copra plantations. They lived in three settlements: East Point (the main settlement on the eastern rim of the atoll), Minni Minni (2.75 mi or 4.5 km north of East Point), and Pointe Marianne (on the western rim). The islanders were forcibly depopulated to the Seychelles and then to Mauritius amid allegations of starvation and intimidation tactics by the U.S. and UK governments, including the alleged killing of island dogs by American soldiers. Ever since their expulsion, the Chagossians have continually asserted their right to return to Diego Garcia. In April 2006, 102 Chagossians were allowed to visit Diego Garcia for a week, to tend to graves and visit their birthplaces.

Now, Diego Garcia is home to a military base jointly operated by the United States and the United Kingdom. The base serves as a naval refueling and support station. It also serves as the home to Maritime Prepositioning Ship Squadron Two, the naval unit responsible for the readiness of the ships in Military Sealift Command Prepositioning Program in the Indian Ocean, a vital strategic asset to the United States.

Diego Garcia also has an air base that supports the largest of modern aircraft. B-52s, other bombers, and aerial refueling tanker aircraft have been deployed to Diego Garcia to execute missions to Iraq in support of the Iraq War. During the 1991 Gulf War, it was home to the 4300 Provisional Bomb Wing, made up of B-52G bombers from Loring AFB and other B-52G bases. Diego Garcia was also used in support of military missions in Afghanistan during Operation Enduring Freedom, and to Iraq again during the 2003 invasion. High-tech portable shelters to support the B-2 bomber were built on the island before the 2003 invasion of Iraq. The B-52s, B-1s and B-2s deployed to Diego Garcia, in anticipation of the second Iraq War carried out the initial aerial bombardment on Baghdad on March 22, 2003. Some of these bombers dropped GPS guided bombs and laser guided 4,200 lb. (1,905 kg) bunker busters in "decapitation strikes" intended to kill Saddam Hussein and other Baath Party officials. Diego Garcia is also a regular deployment site for US Navy P-3C Orion maritime patrol and anti-submarine aircraft.

The base is part of the U.S. Space Surveillance Network, with a three-telescope GEODSS station, and is a NASA Space Shuttle emergency landing site.

Neither the U.S. nor the UK recognizes Diego Garcia as being subject to the African Nuclear Weapons Free Zone Treaty, even though the rest of the Chagos Archipelago is included, suggesting the U.S. and/or UK wishes to maintain the freedom to base nuclear weapons there.

The agreement between the UK and U.S. for the U.S. to use the island as a military base was made in 1966. It specifies that the agreement runs until 2036, but that either government can opt out of the agreement in 2016.

Construction and maintenance of the base's communications equipment, fuel facilities and military hardware is done strictly by military contractors, and inventories of that weaponry are classified. No service-member family dependents are allowed. In 2001, the US Department of Defense said that there were more buildings on Diego Garcia (654) than military personnel.

Strategic importance

During the Cold War era, the United States was keen on establishing a military base in the Indian Ocean. Because of Diego Garcia's proximity to India, a potential ally of the Soviet Union, the United States saw the island as a strategically important one. U.S. military activities in Diego Garcia have caused friction between India and U.S. in the past.

During the Cold War era, various political parties in India repeatedly demanded that the U.S. dismantle the military base as they saw US' naval presence in Diego Garcia as a potential threat to India's dominance of the Indian Ocean.

However, after the end of the Cold War, relations between India and U.S. have improved dramatically. Diego Garcia was the site of several naval exercises between the US and Indian Navy held between 2001 and 2004.

Diego Garcia is also located relatively close to the Middle East, and experienced rapid military build-ups during the beginnings of the Iranian revolution and the Iraqi invasion of Kuwait.

Diego Garcia has several current missions. U.S. Air Force bombers and AWACS surveillance planes operate from the 12,000 foot (3,650 m) runway, and the USAF Space Command has built a satellite tracking station and communications facility.

The atoll also shelters the 14 ships of Marine Prepositioning Squadron Two. These ships carry the equipment and supplies to support a major armed force with light tanks, armored personnel carriers, munitions, fuel, spare parts and even a mobile field hospital. This equipment showed its necessity during the Persian Gulf War, when the Squadron quickly delivered its equipment to Saudi Arabia. There, soldiers flown on air transports from U.S. and European bases quickly unloaded and deployed the pre-positioned material.

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