UK secures Diego Garcia base with Mauritius in 99-year strategic defense deal

On May 22, 2025, the United Kingdom and Mauritius finalized a landmark agreement transferring sovereignty of the Chagos Archipelago to Mauritius, while ensuring the continued operation of the strategically vital UK-US military base on Diego Garcia for at least the next 99 years. 

Under the terms of the treaty, Mauritius gains sovereignty over the entire Chagos Archipelago, including Diego Garcia. However, the UK retains full operational control over Diego Garcia through a 99-year lease agreement, with an option for a 40-year extension. The UK will pay Mauritius £101 million annually, amounting to a total of £3.4 billion over the lease period. 

The base on Diego Garcia has been a cornerstone of UK and US defense strategy for over five decades, providing critical support for operations across the Middle East, East Africa, and South Asia. Its capabilities include a deep-water port, airfield, and advanced communications and surveillance systems, which have been instrumental in counter-terrorism efforts and intelligence gathering. 

The agreement includes provisions to prevent foreign military presence on the outer islands of the archipelago, establishing a 24-nautical-mile buffer zone around Diego Garcia to protect its operations. Additionally, a rigorous joint decision-making process will govern any activities on the wider islands to ensure that they do not disrupt base operations. 

“As the world becomes more dangerous, our military base on Diego Garcia becomes more important,” Defense Secretary John Healey MP stated. “Without this base, our ability to deter terrorists, defend our interests and protect our troops around the world would be at risk. This agreement will safeguard our national and economic security for generations to come.” 

The agreement faced legal challenges from displaced Chagossians, who were not consulted during the negotiations. A High Court injunction temporarily blocked the signing, but it was lifted later the same day, allowing the agreement to proceed. 

The US administration, through Secretary of State Marco Rubio, expressed its support for the agreement. 

“Following a comprehensive interagency review, the Trump Administration determined that this agreement secures the long-term, stable, and effective operation of the joint U.S.-UK military facility at Diego Garcia,” Rubio said in a statement. “This is a critical asset for regional and global security.  President Trump expressed his support for this monumental achievement during his meeting with Prime Minister Starmer at the White House.” 

Recent deployment of USAF B-2 strategic bombers during Operation Rough Rider 

One recent example of Diego Garcia’s enduring operational relevance was its role during Operation Rough Rider in early 2025. As part of the US-led campaign to curb Houthi missile threats in the Red Sea and Gulf of Aden, six B-2 Spirit stealth bombers were deployed to the island’s airfield in March. Their mission focused on striking high-value targets, including launch sites and command infrastructure, in response to increased attacks on international shipping. 

Operation Rough Rider was not without difficulties, though: at least seven MQ-9 Reaper drones were reportedly shot down by Houthi forces, and multiple US aircraft experienced near-miss incidents over contested airspace. 

The operation concluded with a ceasefire agreement in May 2025, after which the B-2s returned to Whiteman Air Force Base in Missouri. However, a contingent of four B-52 bombers and F-15E Strike Eagles remained at Diego Garcia as a strategic deterrent and rapid-response force for the Indo-Pacific and Middle East regions. The post UK secures Diego Garcia base with Mauritius in 99-year strategic defense deal appeared first on AeroTime.

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