Why debate over joint military base in Indian Ocean keeps flaring up Iran factor looming over Diego Garcia

The debate over the British-American joint Diego Garcia military base has resurfaced after US President Donald Trump sharply criticized the United Kingdom’s agreement to transfer sovereignty of the Chagos Islands to Mauritius — despite Washington’s official backing of the deal.

Trump had previously described it as “stupid” and a “big mistake” for UK Prime Minister Keir Starmer to cede sovereignty over the Chagos Archipelago, located roughly halfway between East Africa and Indonesia. He later argued that maintaining control of the islands is essential in the event of a conflict with Iran, as US media recalls.

Posting on Truth Social on February 19, Trump called Washington's relationship with the UK "a strong and powerful one… but prime minister Starmer is losing control of this important Island by claims of entities never known of before.” 

He added: “This land should not be taken away from the UK and, if it is allowed to be, it will be a blight on our Great Ally. We will always be ready, willing, and able to fight for the UK, but they have to remain strong in the face of Wokeism, and other problems put before them.”

Diego Garcia is the largest island in the Chagos Archipelago — a group of around 60 islands — and hosts a critical joint UK-US military base. The island, covering about 30 square kilometers, is administered under a 99-year lease arrangement that allows Britain to maintain operational control of the base even after sovereignty over the archipelago was transferred to Mauritius in May 2025.

Approximately 4,000 personnel — mostly American, with a smaller British contingent overseeing security and customs — are stationed there. For Washington, Diego Garcia is one of the most strategically valuable military facilities in the world. Its remote location in the central Indian Ocean provides:

-Rapid access to the Middle East, East Africa and South Asia

-A secure platform for long-range bombers

-Logistics support for naval operations

-Intelligence and surveillance capabilities

The base has played key roles in US operations in Iraq and Afghanistan and remains central to American force projection across the Indo-Pacific.

What Iran has to do with it

Iran has previously warned that it would target the UK-US base on Diego Garcia if the United States launched military action against Tehran. The island’s location makes it an ideal staging ground for operations involving Iran, particularly given its distance from mainland conflict zones while remaining within striking range via long-range aircraft and naval assets.

A British Foreign Office spokesperson told Sky News that “the agreement to secure the joint UK-US military base on Diego Garcia is crucial to the security of the UK and our key allies, as well as the safety of the British people. The agreement we have reached is the only way to secure the long-term future of this vital military base.”

Starmer equally defended the deal at the time, stating "the strategic location of this base is of the utmost significance to Britain. By agreeing to this deal now, on our terms, we’re securing strong protections, including from malign influence, that will allow the base to operate well into the next century.”

Only this week, a US State Department spokesperson also said that “the United States supports the United Kingdom's decision to proceed with the agreement with Mauritius regarding the Chagos Archipelago,” highlighting a disconnect between the White House’s rhetoric and official US policy.

However, the agreement has triggered fierce debate in London. Conservative Party leader Kemi Badenoch stated that "if our closest ally says so, the Prime Minister should listen. It's time to ditch this terrible deal.”

Reform UK leader and Trump ally Nigel Farage echoed those calls, saying that "Starmer risks alienating our most important ally by handing over the Chagos Islands, the worst deal in British history." 

For Washington, ensuring uninterrupted access and operational control of the base is paramount while the agreement with Mauritius aims to resolve long-running legal challenges for London while preserving the base through a lease framework.

By Nazrin Sadigova