How The UK-Mauritius Deal On Chagos Could Reshape US Military Strategy In The Indian Ocean – Analysis

By Raghvendra Kumar

Introduction: The Context

(FPRI) — Diego Garcia, an atoll and one of the largest of the 52 islands in the middle of the Indian Ocean, is geographically part of the Chagos Archipelago — a British Indian Ocean Territory (BIOT), which is one of the 14 overseas territories of the United Kingdom. However, its sovereignty is contested by Mauritius, an African island state in the Indian Ocean.

Diego Garcia hosts a joint Anglo-American military base with a deep-water port capable of berthing aircraft carriers, a long runway that enables deep-strike operations and accommodates heavy bombers and refueling aircraft, advanced satellite communication facilities essential for real-time command and control, and strategically pre-positioned military support and supplies — making it a key node for logistics, surveillance, intelligence, and strategic deterrence for the United States.

This military base provides the United States with strategic depth and tactical command to project power far beyond its territorial boundaries into regions designated as primary areas of national interest by Washington — as witnessed during the Gulf War (1991), the War on Terror and the invasion of Afghanistan (2001–2021), the Iraq invasion (2003), and, most recently, the US strikes on Houthi rebels in Yemen.

Since 15 March 2025, the United States has launched relentless airstrikes on Houthi rebel hideouts in Yemen, responding to their continued disruption of the free passage of cargo, commercial shipping, and energy supplies in the Red Sea region. Operating in coordination with Hezbollah and backed by state-sponsored support, the Houthis have increasingly weaponized advanced technologies — including drones, missiles, and unmanned surface vessels (USVs) — to threaten vital maritime trade routes. These developments have not only jeopardized US and global interests but also pose serious ramifications for regional security, as state-sponsored non-state actors gain access to sophisticated weapon systems capable of holding critical infrastructure and sea lanes hostage — thereby acquiring the means to destabilize the entire region and turning it into a potential safe haven for transnational organized crime networks (TNOC).

In response, the United States has extensively relied on its strategic base at Diego Garcia to conduct airstrikes and uphold the rules-based international order. The recent deployment of six B-2 stealth bombers, a C-17 military transport aircraft, and several KC-135 refueling tankers is not solely intended to counter the Houthis — it also signals a show of strength and serves as a clear deterrent to Iran and other adversaries that continue to arm and support proxy groups across the region. In such a hostile environment, where regional security is jeopardized by ongoing conflict and instability, testing the current rules-based order and the prevailing balance of power, the Diego Garcia base remains critical to US military strategy in the Indian Ocean. It provides the strategic depth necessary to deter aggression, defend US interests, restore freedom of navigation, and secure vital sea lines of communication.

Diego Garcia is thus a major geostrategic and logistical support base for US interests and operations in the wider Indian Ocean region, particularly amidst shifting geopolitical and strategic dynamics. China has made significant advances in expanding its “sphere of influence” through its Belt and Road Initiative (BRI), a tool of civil–military fusion wherein civilian entities are utilized to support the expansion of China’s military presence.

A case in point: in addition to its first overseas military base in Djibouti, the PRC is involved in the development of 78 ports across Africa, the majority of which are being built to berth naval vessels and function as dual-use facilities. In recent years, the People’s Liberation Army Navy has made port calls and docked at several African ports, including Tamatave (Madagascar), Maputo (Mozambique), Victoria (Seychelles), Durban and Simon’s Town (South Africa), Dar es Salaam (Tanzania), and Doraleh (Djibouti). Chinese troops have also utilized naval and land facilities for various drills, including Tanzania’s Kigamboni Naval Base, Mapinga Comprehensive Military Training Center, and Ngerengere Air Force Base — all built by Chinese firms.

These developments point to a potentially alarming situation in which China is steadily expanding its footprint in a region traditionally dominated by the United States and its allies and like-minded partners. Furthermore, a growing deep-state alignment between Russia, China, and Iran signals an escalating security dilemma for the United States. These countries appear to be leveraging ongoing conflicts and instability to expand their spheres of influence — particularly by supporting Iran’s nuclear program and militarily supporting extremist groups — making it even more critical for the United States to retain its strategic presence and maintain the tactical command necessary for anti-access/area denial (A2/AD) operations. However, as recent UK-Mauritius negotiations over the sovereignty of the Chagos Archipelago progress, the future of this strategic outpost stands at a crossroads, potentially reshaping how the United States navigates the deal and maintains its strategic posture in the region.

Geographical and Historical Context: Diego Garcia, a Strategic Pivot for US Power Projection

Geography manifests in the physical domain and shapes political decisions, economic policies, social dynamics, and military strategies. At the same time, it often acts as one of the most significant determinants influencing international politics, defining a state’s ability to project power or access critical strategic resources. Strategic planners have, therefore, consistently treated geography as a foundational element in securing trade routes, ensuring the flow of energy and resources, and enabling access to distant theatres for power projection and influence.

In this context, island states have long held a significant position in global strategic thought due to their deep maritime character — a view supported by strategic thinkers like Alfred Thayer Mahan, who championed sea power as an essential element for global dominance. Mahan reinforced the idea that island states, by virtue of their maritime positioning, serve as pivotal nodes in shifting regional and international power dynamics. Mahan, therefore, was instrumental in shaping this vision, advocating for a network of coaling/refueling stations and naval bases to secure sea lines of communication and support an expanded navy that the United States might have in the future. His ideas highlighted the strategic utility of island territories in securing maritime dominance. Thus, guided by such strategic thinking, the United States has historically acquired overseas bases wherever its strategic and commercial interests lie, transforming itself into a credible and dominant global force. Even before Mahan, earlier in 1866, Secretary of State William Seward recognized the importance of strategic geographies and negotiated the deal for the purchase of Alaska from Russia. Similarly, Hawaii, the Caribbean, and a future canal zone in Panama were deemed critical to anchor American influence.

However, Mahan’s strategic vision later gained traction within policy circles and military planners, resulting in the United States acquiring bases all around the globe, which became pillars of US maritime dominance and strategic outreach. Currently, Washington has about 750 overseas military bases worldwide. In this long arc of strategic base-building, Diego Garcia stands as a contemporary embodiment of Mahan’s strategy, providing the United States with unparalleled reach into the Indian Ocean region. Strategically located at the junction of the “great maritime highway” connecting key global markets with critical sources of raw materials and energy supplies in Asia and Africa, Diego Garcia plays a vital role in safeguarding US geopolitical, security, trade, and energy interests.

Historically, the island has been a dependency of Mauritius since the 16th century, when the Portuguese first discovered it. Later, in the 18th century, the islands of Mauritius, along with their dependencies, and the Seychelles came under French control. In 1810, the British took control of the island of Mauritius and its dependencies from the French. However, it was after the Treaty of Paris in 1814 that Mauritius, including the Chagos Archipelago, became a British colony. During the Cold War, in 1965, an agreement between the United States and the United Kingdom led to the creation of the BIOT by an Order in Council under the Royal Prerogative. This was done for the purpose of establishing defense and communications facilities aimed at countering the Soviet military presence in the region. Even after Mauritius gained independence from Britain, the Chagos Archipelago, including Diego Garcia, remained part of the BIOT and was later leased to the United States in 1966 for building a joint military facility to enable the United States to respond militarily to contingencies in the Indian Ocean area. Since then, the atoll has evolved into a cornerstone of American power projection in the Indo-Pacific, reinforcing US influence across the Middle East, Africa, and South and Southeast Asia. Diego Garcia thus exemplifies the continuity of a longstanding American grand strategy — anchoring forward operating bases in geopolitically pivotal locations to uphold a rules-based order, deter adversaries, and safeguard global commerce and energy supply chains.

Colonial Legacy and Sovereignty Disputes: Implications for US Military Strategy

Even after Mauritius lawfully completed its decolonization process and was granted independence in 1968, the separation of the Chagos Archipelago from Mauritian territory and the continued administration of the islands by the United Kingdom in 1965 — creating the BIOT, a move widely interpreted as a strategic trade-off for granting Mauritius its independence — gave rise to a longstanding sovereignty dispute. The Government of Mauritius has consistently claimed that the separation was unlawful and has maintained that it has been unable to implement resettlement programs for its nationals — the Chagossians — on the archipelago. The Chagossians are predominantly descendants of enslaved people who were forcibly brought from mainland Africa and Madagascar to the then-uninhabited Chagos islands, where they were made to work on coconut plantations during French and British colonial rule from the 18th to the 20th centuries. After their emancipation, indentured laborers from India arrived. Over generations, this diverse population evolved into a distinct community, developing the Chagossian Creole language, music, and cultural practices.

Diego Garcia’s strategic significance has grown steadily since the Cold War, particularly after the United Kingdom’s gradual withdrawal from its colonies “east of Suez” in the late 1960s and early 1970s. At the time, Britain’s presence in the Indian Ocean was seen by Western powers as a stabilizing force. Its retreat raised concerns in Washington about a potential power vacuum that could destabilize the region and threaten US strategic and commercial interests. In response, the United States identified the Indian Ocean as a key geopolitical arena, particularly amid growing Soviet influence and the emergence of politically fragile, newly independent states. In 1966, an Exchange of Notes with the US government granted Diego Garcia to Washington to meet the defense needs of both countries, for an initial period of 50 years. This agreement included a provision for extension by another 20 years beyond 2016 till 2036, and in 1971, US Navy Seabees arrived to begin constructing a military support facility. Thus, between 1965 and 1973, it is claimed by Mauritius that the United Kingdom and the United States forcibly removed the entire Chagossian population from all inhabited islands of the archipelago — including Diego Garcia, Peros Banhos, and Salomon, resettling them thousands of kilometers away, mostly in Mauritius and the Seychelles — to establish a US-UK military base.

As part of the 1965 agreement, the United Kingdom paid the colony of Mauritius a £3 million grant. Further, in response to the displacement of the local population, during the 1970s and 1980s, more compensation was provided by the United Kingdom to Mauritius (£650,000 in the 1970s and an additional £4 million in the 1980s through a trust fund) for their rehabilitation. However, these measures were widely criticized as inadequate by Mauritius and other social groups, thereby increasing the legal challenges that began to gain traction, jeopardizing the future of this strategic base. Subsequently, in 2000, the UK High Court found that the expulsion of the Chagossians had been unlawful, a decision which was overturned by the House of Lords — then Britain’s highest court — in 2008, marking a significant legal setback for the displaced community and Mauritius. However, in 2010, a leaked US diplomatic cable from May 2009 disclosed by Wikileaks revealed that a UK Foreign Office official had suggested the creation of a “marine protected area” (MPA) around the Chagos islands as a means to “put to rest the paid resettlement claims” by former inhabitants. This strategy backfired and was subsequently challenged by Mauritius, and in 2015 a United Nations tribunal ruled that the United Kingdom had acted illegally in establishing the MPA, as it had failed to consult Mauritius and had unlawfully deprived it of fishing rights.

Despite these international rulings, the UK government in 2016 announced a £40 million support package for Chagossians living in the United Kingdom but continued denying them the right to return to their homeland. In 2019, the International Court of Justice (ICJ), in a landmark advisory opinion, concluded that the United Kingdom’s continued occupation of the Chagos Archipelago was unlawful and ruled that the territory should be returned to Mauritius “as rapidly as possible.” The UN General Assembly overwhelmingly endorsed the ICJ’s ruling, setting a six-month deadline for the withdrawal. However, the United Kingdom refused to comply with the resolution.

The dispute continued to intensify. In 2021, the UN special international maritime court rejected the British claim to sovereignty over the Chagos islands. In the same year, Mauritius’ Prime Minister renewed his call for the United Kingdom to end its “unlawful occupation” of the territory. In 2022, facing mounting international pressure, the United Kingdom agreed to open negotiations with Mauritius regarding the future of the Chagos islands. These discussions culminated in 2024, when the United Kingdom formally agreed to transfer sovereignty of the Chagos Archipelago to Mauritius, thus ending decades of bitter dispute over what was often called Britain’s last African colony. However, the United Kingdom and Mauritius have reached a historic agreement to secure and protect national security as well as safeguard the operation of the strategic military base, which is strategically important for the UK-US positioning in the Indian Ocean region and beyond.

The Way Ahead: Navigating the Diego Garcia Dilemma

The future of Diego Garcia under Mauritian sovereignty carries significant implications for the US military posture in the Indo-Pacific and Middle East. Although the sovereignty dispute over the Chagos Archipelago has garnered increasing international support for Mauritius, and the United Kingdom has ceded to these claims, the United States is expected to maintain unimpeded access to Diego Garcia under existing defense agreements. The continuity of US operations would reaffirm Diego Garcia’s enduring role as a linchpin of American strategy in the Indian Ocean.

Currently serving as the major node in the US military’s logistics chain across the Western Indian Ocean and Arabian Sea, the base supports strategic depth for military operations across multiple combatant commands— CENTCOM, AFRICOM, EUCOM, and INDOPACOM. Diego Garcia hosts 16 US commands, including the Navy Support Facility, enabling rapid deployment, power projection, and logistical support across vast theatres. Historically, it has been central to missions such as the Iran Hostage Crisis (1979–81), the Gulf War (1990–91), Operation Desert Fox (1998) and post-9/11 terror attacks, Operation Enduring Freedom (2001–2002) against al-Qaeda terrorist in Afghanistan, Operation Iraqi Freedom in Iraq (2003) and the recent continued use of “overwhelming, lethal force” by the United States against the Houthi terrorist targets until the Washington achieves its end state as per Chief Pentagon Spokesman Sean Parnell, when the “Houthis pledge to stop attacking our ships and putting American lives at risk.” The island has also facilitated discreet strategic missions — ranging from stealth bomber deployments to the pre-positioning of vital supplies and tactical assets — enhancing US readiness against both state and non-state adversaries. Often described as an “unsinkable aircraft carrier,” Diego Garcia remains irreplaceable to US grand strategy.

Therefore, the evolving sovereignty status of the Chagos Archipelago — particularly Diego Garcia — poses both a challenge and an opportunity for the US strategic posture in the Indian Ocean. The 2024 agreement between the Republic of Mauritius and the United Kingdom marks a significant shift in the legal and diplomatic landscape governing this critical military asset and opens space for an enhanced and comprehensive US–Mauritius strategic defense partnership. Under President Donald Trump’s administration, the United States enters a new phase of strategic diplomacy with Port Louis. The US Department of Defense has welcomed the development, affirming that the agreement “will protect the long-term, secure, and effective operation of the joint US–UK military base on Diego Garcia,” describing it as having played a “critical role in national, regional, and global security” and enabling the United States to “respond to crises and counter complex, challenging security threats.” According to the department, the agreement safeguards “the strategic security interests of the UK, Mauritius, and the US, as well as our partners in the Indo-Pacific region into the next century.” This diplomatic breakthrough signals continuity in mission-critical operations, while also underscoring the need to formalize and institutionalize future basing arrangements through direct engagement with Mauritius. In doing so, it offers scope for renewed impetus to US-Mauritius relations, potentially elevating them into a comprehensive strategic partnership grounded in mutual security interests.

While Mauritius has traditionally maintained close ties with the West and India, its growing economic dependence on China — particularly under the BRI — raises concerns about potential strategic realignmentsunder Beijing’s influence. China could leverage predatory lending and infrastructure development to sway Port Louis’ decisions regarding future military access, intelligence-sharing, or foreign troop deployments in Diego Garcia. There is a risk that Mauritius might adopt a hedging strategy, assuming a more neutral or even non-aligned posture, complicating US long-term basing rights.

Thus, in light of growing strategic competition from China’s expanding presence across the Indian Ocean — from Gwadar to Hambantota to Djibouti — the United States must develop contingency plans for worst-case scenarios, which may include but are not limited to: i) restricted access or lease termination post-2036 (or even earlier); ii) renewed limitations on US military operations from Diego Garcia, such as restrictions on basing nuclear-capable assets, conducting surveillance or strike missions; iii) Chinese efforts to gain access to nearby islands/atolls of the Chagos Archipelago for development that could serve dual-use purposes.

To counter these risks, the United States may consider re-negotiating a long-term security and defense partnership with Mauritius while simultaneously offering economic and developmental incentives. Given India’s traditional and historical linkages with Mauritius and its robust bilateral ties, the United States must take New Delhi into confidence during re-negotiations to ensure a favorable outcome for Washington’s strategic interests. Enhancing India–US military cooperation in the Indian Ocean — through mechanisms such as the Logistics Exchange Memorandum of Agreement (LEMOA) — could also help diversify US basing options.

Moreover, the United States should invest extensively in maritime domain awareness and logistical infrastructure in partner states such as the Seychelles, Kenya, and Oman to diversify its strategic basing options and reduce over-reliance on Diego Garcia. Nonetheless, the Diego Garcia dilemma is not just about basing rights and security imperatives. It also serves as a litmus test for how the United States — as a champion of democracy, human rights, and a rules-based order — navigates its commitments to decolonization, the resettlement of the Chagossians, ecological rehabilitation, and reparative justice. These issues are poised to become central to political debates and will likely be exploited by adversaries through strategic communication networks to portray the United States in a negative light.

Therefore, Washington’s posture on these matters could significantly influence its credibility in the Global South. The current Trump administration must approach this issue pragmatically, with caution and a touch of humanity. In conclusion, Diego Garcia stands at a crossroads — caught between sovereignty claims and strategic choices. Therefore, how the United States navigates this dilemma will reinforce its defense, deterrence, and development capabilities in the Indian Ocean and beyond, serving as a strategic anchor in a region vital for counterterrorism, energy security, trade protection, and great-power competition.

• About the author: Raghvendra Kumar is a Non-Resident Fellow at FPRI’s Africa Program. He holds a Ph.D. and M.Phil. in African Studies from the University of Delhi, along with a Bachelor’s and a Master’s degree in Political Science from Kirori Mal College, University of Delhi. His expertise lies in Africa’s maritime security, the blue economy, and geoeconomic competition, particularly in Africa’s coastal and island states.
• Source: This article was published by FPRI