Diego Garcia is an island shrouded in secrecy. Inaccessible to anyone without pre-approved clearance, it remains notoriously off-limits for almost all civilians. Located in the Indian Ocean, it has been a part of the British Indian Ocean Territory (BIOT) since the defeat of Napoleonic France. The island became a dedicated military base in the 1970s, with the U.S. and UK utilising it for defence. It is home to several U.S. commands and the British Royal Marines.
Although a pivotal support facility during the War on Terror, controversy surrounds Diego Garcia. Tensions between the British and Mauritian governments over the sovereignty of the island are the backdrop for numerous sources claiming that the island housed a CIA black site during the time of the extraordinary rendition programme. Although retaining its strategic significance, the signature of the United Kingdom-Mauritian Joint Statement (UKMJS) in 2024 cast the island’s future in doubt. This Treaty signed the island’s sovereignty back to Mauritius whilst allowing the island’s lease to the UK and U.S. for military purposes. Additionally, rising tensions with China make retaining a Western presence on Diego Garcia even more critical.
Images Sourced From: Senior Airman Rebeca M. Luquin, Senior Airman Nathan G. Bevier
1 Diego Garcia: Geographical Location, Flag, Occupants
1.1 Geographical Location
Diego Garcia, with an area of thirty square kilometres, is the largest of fifty-two islands that form the Chagos Archipelago. Located 1,000 miles from the Indian subcontinent, the island group lies in the centre of the Indian Ocean (7°18′48″S 72°24′40″E / 7.31333°S 72.41111°E). The holiday islands of the Maldives, Seychelles, and Mauritius are in its proximity. [source, source, source]
1.2 Flag
Diego Garcia’s flag is that of the British Indian Ocean Territory (BIOT). It depicts a Union Jack on a blue and white waved background. A palm tree, specimens of which are found all over the island, rises from St. Edward’s Crown. This is the crown for coronations of the British monarchy and is thought to date back to Edward the Confessor, the last Anglo-Saxon king of England. [source, source]
1.3 Occupants
Diego Garcia is host to an exclusively foreign military presence; it does not have a native population. Before the 1970s, around 1,200 agricultural workers, Chagossians or Illois, lived on the island. The plantations closed in 1971, and these individuals relocated to neighbouring islands. As of 2018, approximately 3,000 U.S. and UK military personnel live on the island. Significantly, entry into Diego Garcia is highly restricted and requires U.S. Navy Support Facility clearance. [source, source, source, source]
1.4 Infrastructure
Upgrades on Diego Garcia in the 1970s included two 12,000 foot-runways to support long-range bomber operations, today primarily involving the Northrop B-2 Spirit. [source]
1.4.1 B-2 Bomber
This aircraft is a multi-role bomber that has both conventional and nuclear munitions. The design is low observability, achieved through infrared, acoustic, electromagnetic, visual and radar signatures. Its range is 6,000 nautical miles when un-refueled and 10,000 nautical miles with a single refuelling. Furthermore, the B-2 plays a critical role in U.S. operations. For example, previous missions include that of Operation Allied Force and Operation Iraqi Freedom. During Operation Allied Force, the B-2 destroyed thirty-three percent of Serbian targets in the first eight weeks of the mission. [source, source, source, source]
1.5 Strategic Significance
The proximity of Diego Garcia to the Indian Ocean and North Arabian Sea means it is strategically vital for both the U.S. and British Navy. After the 1979 Islamic Revolution, the U.S. lost a key ally in the region due to the overthrow of the Shah. Diego Garcia allowed for the establishment of a nearby military footprint. Additionally, the Indo-Pacific region is of great geopolitical and socioeconomic importance to China. Therefore, Diego Garcia is a means through which the U.S. and UK can attempt to counter China’s efforts to undermine the Western-rules-based order. [source, source]
2 Diego Garcia: History
2.1 Discovery
Portuguese explorers discovered Diego Garcia in the early 1500s, and the French claimed the island in the 1700s. The island became a British territory after Napoleonic France’s defeat and the subsequent Treaty of Paris in 1814. [source, source]
2.2 British Rule
After the French handed the island to the British, it constituted a British Indian Ocean Territory (BIOT). The 640,000 square kilometres of ocean and land constituting the archipelago in which the island is located is administered from London. Mauritius gained independence in 1968, but the British retained control of Diego Garcia. The shutting of coconut plantations in 1971 led to mass unemployment of the workers on the island. In the same year, the British Commissioner enacted the Immigration Ordinance, making it unlawful for a person to enter or remain in a BIOT without permission. This marked the beginning of the secrecy surrounding Diego Garcia today. [source, source, source]
2.3 1966 Notes of Issue
In 1966, an agreement was signed between the UK and the U.S., making Diego Garcia available for both government’s defence needs. Although the UK’s acceptance of a U.S. military presence on the island is motivated by a desire for close military ties with the U.S., it was also motivated by finances. Allowing the U.S. to operate from the island led to heavily discounted British purchases of Polaris nuclear missiles. [source, source]
2.3.1 Polaris Nuclear Missiles
The Polaris was the U.S. Navy’s first submarine-launched missile. The missile had a range of 2,500 kilometres and carried three W58 nuclear warheads, each yielding 200 kilotons. Britain initially used the missiles on the HMS Resolution, the first British-class nuclear-powered ballistic missile submarine. [source, source, source]
3 Diego Garcia as a Military Base
3.1 US Navy Support Facility
The Support Facility on Diego Garcia began in 1966 after the Notes of Issue. In January 1971, the U.S. Naval Construction Force (aka “Seabees”) arrived on the island, beginning the construction of the U.S. Naval base that remains today. The Support Facility in Diego Garcia supports operational forces in the Indian Ocean and Persian Gulf to pursue national policy objectives. With the help of the Seabees, the U.S. established a permanent presence on the island in only two years. [source, source, source, source, source]
3.2 US Navy Commands on Diego Garcia
Diego Garcia hosts sixteen commands, with the Naval Support Facility as a host command.
- US Naval Computer and Telecommunications Station Far East Detachment (NCTSFE DET)
- Military Sealift Command Office (MSCO) Maritime Pre-positioning Ship Squdron (COMPSRON) TWO
- Branch Health Clinic (BHC)
- American Forces Network (AFN)
- Public Works Department (PWD), Naval Facilities Engineering Command Far East (NAVFAC FE)
- US Fleet and Industrial Supply Centre (FISC)
- Air Mobility Command (AMC)
- Delta 6, 21st Space Operations Squadron Detachment 1 – Diego Garcia Remote Tracking Station (DGS)
- Delta 8, 2nd Space Operations Squadron OL-D, GPS
- Delta 2, 15th Space Surveillance Squadron Detachment 2, GEODSS
- Pacific Air Force (PACAF) Detachment ONE, 36 Mission Support Group (MSG). [source]
In particular, Delta commands indicate that the island functions as more than just a military support base.
3.2.1 Delta 6, 21st Space Operations Squadron Detachment 1 (Diego Garcia Tracking Station)
Call sign “REEF”, Diego Garcia Tracking Station (DGS) is a unit of Space Delta 6, Space Operations Command. It is one of seven satellite remote tracking stations in the Satellite Control Network. Its mission is to execute on-demand, real-time command and control (C2) operations. [source, source]
3.2.2 Delta 8, 2nd Space Operation Squadron OL-D, GPS
Delta 8 performs the command and control mission for thirty-seven satellite Global Positioning Systems. Through this, they provide precise, three-dimensional positioning and navigation utilised by military and civilian users. These GPS satellites also carry a secondary Nuclear Detection System that can detect electromagnetic signals caused by a nuclear blast. [source, source]
4.2.3 Delta 2, 15th Space Surveillance Squadron Detachment 2, DEODSS
This detachment dedicates itself to Ground-based Electro-Optical Deep Space Surveillance (GEODSS). Their primary mission is to detect, track and identify all tasked space objects within its area. Each one of the detachment sites operates three one-meter telescopes, producing more than 6,000 metric observations per day. [source, source]
3.3 Diego Garcia and the Iranian Revolution
Iran’s Islamic Revolution in 1979 overthrew the Shah, an ally of the United States. The revolution redrew the map of global alliances, and Diego Garcia underwent the largest expansion of any U.S. military location since the Vietnam War. Iran’s modernisation under the Shah directly benefited the United States, including the purchase of more than $16 billion in arms between 1972 and 1977. Although losing a key ally in the Middle East, the U.S. doubled down on its investment in Diego Garcia, ensuring that it could support any future missions in the region. Additionally, the island’s strength was significant due to the anti-American sentiment the new Islamic Republic espoused. [source, source]
3.4 Diego Garcia and the War on Terror
After the terrorist attacks of 11 September 2001, Diego Garcia played a critical role in the first airstrike in Afghanistan. Tankers operating on the island refuelled B-2 Bombers flying from U.S. bases. Furthermore, during this period, Diego Garcia underwent greater expansion, with an additional two thousand Air Force personnel stationed there. During the ensuing “War on Terror,” Diego Garcia housed the aircraft dispatched directly to Afghanistan and Iraq. [source, source, source]
3.4.1 Extraordinary Rendition Programme
During the War on Terror, the U.S. and its allies detained hundreds of individuals and transported them to secret prisons for interrogation. Diego Garcia is suspected to be one such location. The practice of extraordinary rendition involves snatching targets from their home nations and transferring them to detention facilities in third countries. This allows the circumvention of traditional judicial proceedings that apply to U.S. prisoners, treating the captives more like prisoners of war.
The UK government confirmed in 2008 that rendition flights carrying terror suspects, most notably Khalid Sheikh Mohammed, landed on the island in 2002. Subsequently, the US Senate Select Committee on Intelligence further investigated the involvement of Diego Garcia during the extraordinary rendition programme. During this time, British diplomats held over twenty meetings with Senate members to prevent the disclosure of Britain’s role. However, as a BIOT, any presence of detainees on the island was done with the consent of London, as the Senate report concluded. [source, source, source, source]
4 Diego Garcia: United Kingdom-Mauritian Joint Statement
4.1 Background
The island’s history has led to a lengthy battle for sovereignty between the United Kingdom and Mauritius. However, the need to maintain positive relationships with Marutius has increased in recent years. Positive relations are necessary due to strengthened ties between Beijing and other regional islands. [source]
4.2 Statement
On 03 October 2024, the United Kingdom signed a deal with Mauritius, granting it sovereignty while allowing the UK military to remain on the island for an initial period of ninety-nine years. Although not yet ratified, many Western states see the treaty as a win for the rules-based international order: a successful counter to Chinese expansion. [source, source]
4.3 U.S. Response
The U.S. response to the UKMJS is positive, at least in public. Former Secretary of State Anthony Bliken reiterated the strategic importance of keeping the island under UK-U.S. jurisdiction. However, the close ties formed between the Mauritian government and China, including the signing of a Free Trade Agreement, creates concern in Washington. [source, source]
4.4 Implications
Navin Ramgoolam, the newly elected Mauritanian prime minister, called for the deal’s renegotiation upon his arrival in office. Stating the need for greater financial reimbursement, the United Kingdom’s part in the treaty is now in the hands of the Mauritian government. However, the signing over of sovereignty of such a critical strategic asset may complicate Britain’s future a major power. The loss of the island as a BIOT, although maintaining a military presence, casts the future role of the island in doubt. [source, source]
5 The Future of Diego Garcia
When ratified, the details of the UKMJS Treaty will clarify Diego Garcia’s future. However, the treaty will remain a source of tension between the rules-based international order and disruptive powers such as China and Iran.
5.1 China
China’s rising power makes the Indo-Pacific region more dangerous. As one of only two U.S. bomber bases in the region, Diego Garcia is critical for any future conflict over Taiwan. Predominantly due to the island’s strategic location, the maintenance of U.S. presence on the base allows the projection of Western power within the region. Additionally, the U.S. interest in Taiwan stems from the desire to maintain the status quo, desiring neither independence nor Chinese incursion. Conversely, China’s interest stems from the desire to unify the island with the mainland, also motivated by the desire to prevent a Western presence so close to its borders. Furthermore, Taiwan’s role in technological development is also critical, as the country produces most of the world’s semiconductors. Diego Garcia allows the U.S. to observe developments in the region whilst remaining close enough to take action should it be required. [source, source]
5.2 Iran
As with China, increasing tensions with Iran ensure that Diego Garcia remains a key strategic location for the U.S. and UK. Hence, U.S. President Donald Trump’s recent campaign against Iran seeks to drive its oil exports to zero to prevent Tehran from obtaining a nuclear weapon. Significantly, the United Nations nuclear watchdog has reported that Iran is accelerating its enrichment of uranium to up to 60%, 30%, away from the level required for weapons-grade level. Although the U.S. and the UK have several military bases in the Middle East, including Oman, Yemen and the United Arab Emirates, these do not align with the U.S. “Strategic Islands Concept.” This policy seeks to build military bases away from any potential anti-Western, anti-American sentiment. [source, source, source, source].
6 Conclusion
Diego Garcia’s history as a key strategic location shows no sign of waning. Undoubtedly, China’s opposition to the Western world order ensures that the island remains a necessary military outpoint for the U.S. and the UK. However, the island’s past casts shadows over its future. Although the UKMJS allows the lease of the island to the UK and U.S. militaries for another ninety-nine years, Mauritian sovereignty increases the ability of China to gain further influence. Furthermore, calls from the Mauritian Prime Minister to renegotiate the Treaty have caused further anxiety for Washington and London. As the Indian Ocean and North Arabian Sea become increasingly key areas due to rising tensions with China and Iran, it is more important than ever that Diego Garcia can keep its secrets.
