UK blocks US use of RAF bases for Iran strike, Chagos deal faces fresh strain

The United Kingdom has declined a US request to launch potential military operations against Iran from British air bases, a decision that could add strain to ongoing negotiations over the future of the Chagos Islands.

UK Prime Minister Keir Starmer’s government refused to authorise American long-range strike missions from RAF Fairford near Swindon, citing concerns that supporting a pre-emptive attack on Iran might conflict with international law. The move comes as Washington increases its military presence in the Middle East and weighs contingency plans targeting Tehran.

Diego Garcia at the centre of tensions

The dispute has also intensified scrutiny over Diego Garcia, the joint UK–US base in the Chagos Islands, considered a key strategic asset for long-distance operations in both the Middle East and the Indo-Pacific.

Under existing agreements, US forces operating from Diego Garcia are only required to notify the UK. However, any use of RAF bases within Britain requires direct approval from London — approval that has now been denied.

The UK’s hesitation reflects longstanding caution. Following legal interpretations adopted after 2001, British policy holds that a country can share liability if it knowingly assists in military action later deemed unlawful. In previous US strikes involving Iran, Britain limited its involvement to defensive support rather than direct participation.

Trump criticises the UK decision

US President Donald Trump publicly criticised the UK’s position and urged Britain not to proceed with plans to transfer sovereignty of the Chagos Islands to Mauritius.

In a post on Truth Social, Trump said the United States might require access to Diego Garcia and RAF Fairford "in order to eradicate a potential attack by a highly unstable and dangerous Regime."

The proposed agreement would see Britain hand control of the Chagos Islands to Mauritius while leasing back Diego Garcia for 99 years at a reported cost of £35 billion. Washington views the base as central to its strategic footprint across the region.

Trump, who has alternated between supporting and criticising the arrangement, reiterated his opposition, writing, "DO NOT GIVE AWAY DIEGO GARCIA!" He has previously described the deal as a "big mistake."

With regional tensions rising, the episode underscores the delicate balance between legal obligations, strategic priorities and diplomatic ties between long-standing allies.