Is Diego Garcia at Risk of Slipping from Washington's Grasp?

September 19, 2017 Topic: Security Region: Asia Tags: PentagonMilitaryWarU.S. NavyWeaponsTechnology

Is Diego Garcia at Risk of Slipping from Washington's Grasp?

Diego Garcia’s strategic importance cannot be overstated because the Defense Department has, in general, been gradually reducing its overseas presence throughout the world.

The Law of the Sea Arbitral Tribunal Ruling

The tribunal ultimately found in Mauritius’ favor since the original agreements detaching the Chagos from the Mauritius territorial area recognized Mauritius’ rights to exploit the economic resources in the exclusive economic zone of the Chagos Islands and the continental shelf. Given that agreement, Great Britain was “stopped” from taking any action that would compromise Mauritius’ legal rights to fish in those waters. The tribunal also went a step further to chastise the UK for its assertion of sovereignty even though Mauritius has been fishing in the waters for many years.

The tribunal declined to rule on the question of whether the extension of the lease was appropriate (because the Lancaster House Agreement didn’t explicitly state that the rights to retain the Chagos Islands was dependent on the UK’s need to use it for defense purposes), but it did suggest that the promulgation of a MPA to prevent Mauritius from being able to pursue its claims was an action that was not taken in good faith—reinforced because of some leaked “WikiLeaks” diplomatic cables, which suggested that the MPA was established to prevent anyone from returning.

The UN General Assembly and the World Court

The UK’s problem didn’t end with the arbitration. As noted in the introduction, Mauritius pressed its claim to reclaim sovereignty over the Chagos Islands in the UN General Assembly (UNGA). It took this action at the UNGA because any action in the Security Council would be subject to veto by either the United States or Great Britain. It is interesting, from a legal perspective, that Mauritius took this particular approach (even though they are represented by skilled U.S. counsel) since the Permanent Court of Arbitration panel made findings that the collection of “Lancaster House” undertakings were “international obligations” and the Lancaster agreement suggests that in exchange for the UK’s various concessions that the “decision on the need to retain the islands must rest entirely with the United Kingdom Government and it would not (repeat not) be open to the Government of Mauritius to raise the matter or press for the return of the islands on its own initiative.” It will be interesting whether the International Court of Justice applies the same estoppel arguments to Mauritius that it did to the United Kingdom in the arbitration case. It is unlikely that the court will deterred by the actual language in the Lancaster House agreements because of the growing body of international law and policy, which favors the self-determination rights of former colonies and indigenous residents over their former colonial rulers.

What’s Next?

The problem isn’t the lease between the United States and the UK. It’s the landlord. Or more precisely, will the UK continue to be the landlord or will it be legally or politically pressured via an adverse court decision to divest the vestiges of its colonial holdings?

International Court of Justice advisory opinions are not legally binding; however, if there was a verdict in favor of Mauritius, then that would put a lot of pressure on the UK to cede its rights to the Chagos Islands. At the very least, it would put pressure on the United States and the UK to negotiate a new basing agreement with the United States in which Mauritius has a greater say in the terms of U.S. basing arrangement or the types of things that occur on the base.    Mauritius would undoubtedly assert return rights (or some suitable substitute arrangements) on behalf of the Chagossians that still remain in Mauritius following their removal from the islands in 1973. The UK and United States both believed that Indian government could play a constructive role in getting Mauritius to tread carefully and asked for help; however, the Indian representative to the UN supported the UNGA resolution as a “matter of principle for India to uphold the process of decolonization and the respect for sovereignty of nations.” Given that India has been actively increasing military ties with the United States mostly because of concerns with China and signed a ten-year defense framework agreement, it is curious that India insisted on voting against the UK, and by extension, the U.S. presence in Diego Garcia. Should India ever require U.S. military assistance in the India Ocean, some portion of that support would likely come from the island.

Mauritius certainly has a strong economic reason to reacquire the sixty square kilometers of the Chagos Islands as part of greater Mauritius since it is surrounded by thousands of square kilometers of coral reefs and the British Indian Ocean Territory exclusive economic zone for management of marine resources, (in the water column and seabed) which is roughly six hundred thousand square kilometers—more than twice the total UK land area. This marine space includes mid-ocean ridges, trenches and abyssal plains, as well as coral reefs, atolls and banks. It contains one of the few undamaged Indian Ocean coral reefs and its coral reef fisheries are more abundant than in other Indian Ocean locations; however, there is considerable poaching of turtles, sharks, sea cucumbers and other marine life. No data could be found on whether the seabed areas in and around (up to two hundred nautical miles seaward) the archipelago, contain hydrocarbon or other mineral resources. The archipelago’s isolation, unique history as a coconut-oil plantation, and closed military area, all militate against the possibility that there has been active prospecting. Given that, Mauritius is probably eager to learn whether the waters near the Chagos Islands have oil and gas that it can exploit.


It is very unclear if policy officials in the United States are heavily focusing on the recent legal and political events that have occurred in three separate venues: the UK courts, the Permanent Court of Arbitration, and now the UN General Assembly. When viewed in isolation, these problems are manageable; but, when put into a larger context of possible Mauritian territorial ambitions, it is clear that the United States and the UK will need to redouble their efforts to deal with the issue of displaced Chagossians and the economic aspirations of Mauritius. The United States arguably has more to lose in this battle over sovereignty and it would do well to help try and craft a solution that puts it on the right side of this issue because Diego Garcia is irreplaceable real estate. Helping to resettle the displaced Chagossians on their ancestral lands and providing economic incentives to Mauritius—such as unrestricted fishing and mineral rights—may be what is necessary for the United States to retain its ability to operate freely from the island. Also, convincing India that it should respond positively to U.S. and UK overtures to Mauritius would appear to be in India’s best interests if it wants a more robust defense relationship with Washington.

Mark Rosen is the senior vice president and general counsel at CNA. This article represents his personal views. None of the opinions expressed herein should be taken as the opinion of CNA or any of its sponsors.

Image: A B-1 Lancer prepares to connect with a KC-135 Stratotanker refueling boom over the Indian Ocean on July 7. The B-1 was flying a close-air-support mission in support of Operation Enduring Freedom. Wikimedia Commons.


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