Why Britain opposes U.S. use of its bases against Iran?

Pars Today – Britain opposes any use of its military bases by the United States for potential attacks against Iran.

According to Pars Today citing Bloomberg, informed sources said Britain has refused to grant permission for the use of its bases for any U.S. strike on Iran. The decision reportedly faced opposition from senior military commanders and members of the Conservative Party.

The Times and other media outlets also reported that the British government has denied U.S. requests to use its bases.

The decision is said to be linked to concerns over international law and other considerations. UK Defence Secretary John Healey said last month in the House of Commons that the use of Britain’s military bases for operational purposes requires a “legal foundation and political rationale for any possible activity.”

It has also been suggested that the withdrawal of support by Donald Trump from Britain’s agreement to transfer the Chagos Islands to Mauritius is linked to London’s refusal to authorize the use of the Diego Garcia base for an attack on Iran.

According to Daily Mail, senior British military officials urged Keir Starmer on February 20 to prioritize national security and allow Donald Trump to use British bases for a possible attack on Iran.

However, the British Prime Minister’s Office has not granted the United States permission to carry out airstrikes from bases located in British territory or its overseas possessions.

This message was reiterated on February 20 by Yvette Cooper during a meeting with Marco Rubio in Washington, D.C.. She told her American counterpart that Britain supports “diplomatic and economic pressure” on Iran.

According to Bloomberg, the United States has increased military equipment in West Asia to intensify pressure on Iran.

Former U.S. President Donald Trump said on Wednesday that the Diego Garcia base in the Indian Ocean and the RAF Fairford in Suffolk could play a critical role.

Trump specifically sought the use of the British Royal Air Force base and the base on the British overseas territory of the Chagos Islands.

However, following a series of diplomatic countermeasures over the future of the Chagos Islands—which include Diego Garcia—British authorities blocked the U.S. plans.

The dispute escalated after the United Kingdom raised concerns about the legality of potential airstrikes planned by the United States. London warned that if such strikes are deemed unlawful under international law, it could be accused of facilitating illegal military action.

The Chagos Islands, located about 3,200 km off the eastern coast of Africa, host the strategic Diego Garcia facility, which is jointly used by the United Kingdom and the United States. The base allows military operations to be conducted more easily across West Asia and parts of Asia.

In February 2026, British authorities reportedly rejected U.S. requests to use their bases for a potential attack on Iran. The main reasons behind London’s position include:

• Concern over alleged violations of international law: The primary justification cited was London’s fear of being complicit in an operation it considers potentially lacking legal legitimacy. British officials reportedly believe that a U.S. strike on Iran without an imminent threat could be interpreted as a breach of international law. Under international law, a state that knowingly facilitates an unlawful military action may share responsibility for it.

• Requirement for prior authorization: Under longstanding agreements between the two countries, British military facilities—including RAF Fairford within Britain and the overseas base in the Indian Ocean—require explicit approval from the British government before U.S. forces can conduct any military operation. In this case, such authorization was not granted.
• Shift in Washington’s rhetoric and Trump’s reaction: While British policy favors a diplomacy- and economic-pressure-based approach toward Iran, Donald Trump has openly threatened military action. He even wrote on Truth Social that the use of British bases might be necessary to eliminate what he called the Iranian threat. This divergence in strategic outlook has contributed to rising tensions.

• Link to the Chagos Islands dispute: The disagreement is also tied to the broader issue of transferring sovereignty over the Chagos Islands (including Diego Garcia) to Mauritius. Donald Trump, who had previously supported the agreement, later described London’s stance as a “major mistake” after Britain refused permission for the use of its bases. This shift underscores how the issue of British military facilities has become intertwined with other diplomatic disputes between London and Washington.

Ultimately, the British government opted for a cautious approach to avoid being complicit in an operation it viewed as legally and politically risky, and instead emphasized diplomatic solutions.