America’s Interest in Diego Garcia

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Editor’s Note: A version of this article was originally published by The Interpreter, which is published by the Lowy Institute, an independent, nonpartisan think tank based in Sydney. War on the Rocks is proud to be publishing select articles from The Interpreter.


Diego Garcia is America’s major geostrategic and logistics support base in the Indian Ocean. Sovereignty over the island is increasingly being challenged by Mauritius, but it seems unlikely that Washington would be interested in doing a deal that would facilitate its transfer.

The base has its origins in the 1960s as decolonization swept over the region and Soviet influence grew in many of the newly independent countries. But it was China, not the Soviet Union, that spurred Washington to focus on acquiring a base. The policy trigger was the 1962 Sino-Indian War, when Prime Minister Jawaharlal Nehru had pressed Washington for military assistance to India, including an urgent request for U.S. air power to actually intervene. President Kennedy was not willing to go that far, and decided to dispatch the U.S. aircraft carrier USS Kitty Hawk to provide air support if China drove south to Calcutta — but a ceasefire was reached before it arrived.

Diego Garcia Selected

By 1964, a regional survey judged that Diego Garcia — an atoll in the Chagos Archipelago that was an administrative dependency of the distant British colony of Mauritius, some 1155 nautical miles of open ocean away — was best suited. It had a lagoon and land that could support an airfield and other infrastructure, and its remoteness satisfied Washington’s desire to make itself immune from the nationalist pressures of the day.

To insulate Diego Garcia from passing into the hands of a non-aligned government, London detached the Chagos from Mauritius’ colonial administration and created a new entity known as the British Indian Ocean Territory (BIOT). In 1966, London agreed to make Diego Garcia available to the United States for defense purposes for 50 years.

Location, Location, Location

In real estate, the three most important considerations when valuing property are location, location, and location. Diego Garcia more than satisfies these criteria. It is situated near the center of the Indian Ocean, within striking distance of virtually all maritime choke points, vital sea lines of communication, and potential Chinese naval bases in the region: Djibouti and the Bab al Mandeb (2170 nautical miles); the Strait of Hormuz (2240 nautical miles); Gwadar, Pakistan (2030 nautical miles); the Eight Degree Channel between India and the Maldives (895 nautical miles); Hambantota, Sri Lanka (1550 nautical miles); Kyaukphyu, Myanmar (2030 nautical miles); the Strait of Malacca (1770 nautical miles); and Lombok Strait (2625 nautical miles).

It is a perfect base for U.S. Navy maritime patrol aircraft and especially U.S Air Force heavy bombers. All the locations mentioned above are within unrefueled combat range of B-1B and B-52H bombers. (B-2s with an advertised combat range of 6000 nautical miles are generally deployed from the United States, but have been deployed to Diego Garcia in the past.) U.S. Air Force bombers and tankers have conducted combat missions in support of U.S. combat operations throughout Southwest Asia since 1991.

Since the mid-1980s, the base has boasted a wharf and facilities suitable for an aircraft carrier, and a lagoon that provides anchorages for other warships and ships loaded with prepositioned equipment. The U.S. Navy often stations a submarine tender (a repair and logistics ship) to support deployed attack submarines. During the Cold War, Diego Garcia was a perfect base for long-range U.S. Navy anti-submarine Warfare (ASW) aircraft that tracked Soviet submarines crossing the Indian Ocean from the Russian Far East to the Northern Arabian Sea.

The China Factor

In 1962 it was China’s military action that initiated the process that has led to today’s base at Diego Garcia and today it is China’s Indian Ocean military footprint that increases the value of Diego Garcia beyond its continuing role in supporting US military operations in the Persian Gulf region. The PLA Navy has maintained a modest presence in the western Indian Ocean for over ten years, and China’s recently established base in Djibouti is judged by the U.S. Department of Defense to be only the first of several. China’s most important sea lines of communications (SLOCs) traverse the Indian Ocean and play a key role in Beijing’s prime strategic and economic program, the Belt and Road Initiative.

Sovereignty Chickens Come Home to Roost

But what seemed to be a tidy solution in the 1960s to Washington’s desire for a base isolated from the uncertainties of potentially fickle, newly independent states appears less so now.

Mauritius has long chaffed at what it considers to be the illegal detachment of the Chagos. In 2019, after decades of legal maneuvering, the International Court of Justice (ICJ) concluded that Britain should cede Chagos to Mauritius. The U.N. General Assembly echoed this finding, concluding that the United Kingdom’s decolonization of Mauritius was “incomplete,” a seemingly contrived finding, and adopted a non-binding resolution that demanded the United Kingdom unconditionally withdraw its “colonial” administration within six months.

London did no such thing, and responded it had “no doubt as to our sovereignty over BIOT [British Indian Ocean territory], which has been under continuous British sovereignty since 1814. … Mauritius has never held sovereignty over the BIOT, and the UK does not recognise its claim.”

What Is to Be Done?

The Mauritius government has been relatively self-effacing in its public comments, suggesting it has no intention of demanding the dismantling of the base. Officials have said that Mauritius accepts the future of the base and would be willing to enter into a long-term agreement. The fact that the United States pays $63 million per annum for rights to a more modest facility in Djibouti has undoubtedly not been lost on officials in Port Louis.

A deal with Mauritius seems possible, but would Washington be interested in such an outcome? Probably not, as putting sovereignty into the hands of a landlord who overnight could order Washington to vacate introduces too much uncertainty. If the United States leaves or is evicted, Mauritius would likely not lose its rent since there are at least two other possible tenants, India or China. This provides Port Louis with considerable leverage. Washington has been silent since the U.N. vote, but its written statement to the International Court of Justice (ICJ) makes its position clear: “In 2016, there were discussions between the United Kingdom and the United States concerning the continuing importance of the joint base,” the statement said in a footnote. “Neither party gave notice to terminate (the lease agreement) and the Agreement remains in force until 2036.”



Rear Adm. (Ret.) Michael McDevitt is a Senior Fellow at CNA, a Washington-area nonprofit research and analysis company. He has been involved in U.S. security policy and strategy in the Asia-Pacific for the last 30 years, in both government policy positions and, following his retirement from the U.S. Navy, as an analyst and research director. During his 34-year Navy career he had four at-sea warship commands, including an aircraft carrier battle group. He was the Director of the East Asia and Pacific policy office during the George H.W. Bush administration, and also served as the Director of Strategy and Policy (J-5) for U.S. Pacific Command. His last assignment before retirement was as commandant of the National War College in Washington, DC. He is a graduate of the University of Southern California and Georgetown University, where his MA focused on U.S. East Asian diplomatic history.

Image: U.S. Navy (Photo by Mass Communication Specialist 1st Class Ryan B. Tabios)