The future of the strategically vital Diego Garcia atoll hangs in the balance as the United Kingdom navigates a complex agreement to transfer sovereignty to Mauritius while maintaining a long-term lease for the island’s joint UK-US military base. The deal, initially signed in May 2025, has drawn sharp criticism from Washington, most notably from former US President Donald Trump, who has repeatedly questioned its wisdom and warned against relinquishing control of the key military asset.
Under the terms of the agreement, the UK will formally recognize Mauritius’ sovereignty over the Chagos Archipelago, a collection of over 60 islands in the Indian Ocean. In return, the UK will secure a 99-year lease on Diego Garcia, ensuring continued access to the base, which has played a crucial role in military operations across the Middle East, East Africa and the Indo-Pacific region. The UK is committed to paying Mauritius approximately £3.4 billion over the lease period, with payments escalating in the initial years.
President Trump’s recent interventions have injected uncertainty into the process. Initially backing the agreement after initial criticism, he then attacked it again via social media, stating that Prime Minister Keir Starmer should not “lose control” of Diego Garcia. This fluctuating stance prompted a pause in the parliamentary ratification process in the UK, despite earlier endorsements from the US State Department. , the State Department reiterated its support for the agreement, but the shadow of Trump’s disapproval continues to loom.
The core of the controversy lies in concerns over the potential for diminished control over the base and the possibility of increased strategic competition in the region. Critics argue that ceding sovereignty to Mauritius could open the door to Chinese influence, potentially leading to surveillance activities or even the establishment of a Chinese military presence in the archipelago. However, proponents of the deal maintain that the agreement includes robust safeguards to prevent such scenarios.
The Chagos agreement directly addresses concerns about foreign military presence. It stipulates that the deployment of foreign security forces within the archipelago requires authorization from both the UK and Mauritius. This provision extends to civilian personnel engaged in activities that could pose a security risk, such as those operating under China’s “civil-military fusion strategy.” the agreement outlines a cooperative framework for preventing unauthorized activities, allowing for unilateral or joint action to address potential threats.
Addressing concerns about infrastructure development, the agreement mandates that any construction projects within the Chagos Islands require the consent of the UK. This control extends to a wide range of structures, from private residences to military installations, effectively preventing Mauritius from unilaterally establishing a foreign base. Should Mauritius attempt to circumvent these provisions, the UK retains the right to intervene and prevent such development, without triggering a breach of the agreement.
The agreement also addresses the sensitive issue of nuclear weapons. While Mauritius has a standing commitment under the Treaty of Pelindaba to prohibit the “stationing” of nuclear weapons on its territory, the agreement’s provisions regarding existing international obligations and arrangements are open to interpretation. Some argue that this allows the UK and the US to continue utilizing Diego Garcia as a potential staging ground for nuclear-armed assets, while adhering to the spirit of the treaty. The UK and US maintain a long-standing policy of neither confirming nor denying the presence of nuclear weapons on the island.
Concerns about potential inspections under the Treaty of Pelindaba are also mitigated by the agreement. The UK is not a party to the treaty and is therefore not bound by its inspection provisions. The agreement explicitly states that Mauritius’ retained rights over Diego Garcia are to be exercised with the consent of the UK, effectively preventing unilateral inspections.
the long-term security of the Diego Garcia base rests on US military power. However, the Chagos agreement offers a crucial layer of legitimacy for the US presence, addressing concerns among allies and adversaries alike. By resolving a long-standing colonial dispute and establishing a clear legal framework for the base’s operation, the agreement provides a more sustainable foundation for continued US-UK cooperation in the region.
Despite the safeguards embedded within the agreement, the possibility of Mauritius seeking to terminate it remains a concern for some. However, the agreement outlines narrow and precisely defined grounds for termination, limited to non-payment by the UK, an armed attack on Mauritius, or an armed attack emanating from Diego Garcia. Even in such scenarios, the agreement provides for a dispute resolution mechanism, including binding arbitration, to prevent unilateral action.
The situation remains fluid, with President Trump’s unpredictable pronouncements continuing to cast a shadow over the deal. The UK government is carefully weighing its options, balancing its commitment to the agreement with the need to maintain a strong relationship with the United States. As the ratification process remains paused, the future of Diego Garcia – and its strategic importance to both the UK and the US – remains uncertain.
