British PM refuses to let US use Diego Garcia base for air strikes on Iran

British Prime Minister Keir Starmer has refused President Donald Trump’s request to allow American forces to use two military bases of the United Kingdom for potential strikes on Iran, The Times reported, marking a rare point of strategic friction between the two long-standing NATO allies.

Starmer told Trump that allowing the use of Diego Garcia, in the central Indian Ocean, and Royal Air Force (RAF) station Fairford, England, for a pre-emptive strike would breach international law, the British newspaper reported, citing UK government sources.

  Under established UK-US defence agreements, any military operation against a third country launched from British-controlled territory must receive prior consent from the British government.

The disagreement reportedly prompted Trump to withdraw support for the UK’s proposal to transfer sovereignty of the Chagos Islands, of which Diego Garcia is a part, to Mauritius. In a post on Truth Social, Trump said accessing Diego Garcia and Fairford might become necessary “to eradicate a potential attack by a highly unstable and dangerous regime,” referring to Iran.

“They can’t have a nuclear weapon. Very simple,” he said, adding that the world would know “within 10 days” whether diplomacy would succeed.

“Should Iran decide not to make a deal, it may be necessary for the United States to use Diego Garcia, and the Airfield located in Fairford,” Trump wrote on Truth Social, adding that Iran “can’t have a nuclear weapon.” He argued that Tehran’s actions could potentially threaten the UK and other American allies.

However, Starmer is reportedly wary of becoming complicit in any pre-emptive military action. British officials are concerned that international law does not distinguish between a state carrying out a strike and one providing support if it has “knowledge of the circumstances of the internationally wrongful act,” The Times said.

Why does the US need these bases?

Diego Garcia and RAF Fairford are critical to America’s long-range military strike plans.

As a forward-operating base, Diego Garcia’s strategic location enables US aircraft to reach Iranian targets without launching from the mainland, significantly reducing flight times and reliance on mid-air refuelling. 

RAF Fairford is the only European airfield specifically designed to support long-range US heavy bombers such as the B-52 Stratofortress, B-1 Lancer and B-2 Spirit. It is positioned closer to West Asia than the US, enabling faster sortie generation and offering operational flexibility in a sustained air campaign.

In essence, access to the two bases would allow the US to project power more efficiently, maintain persistent strike capability and distribute assets across multiple launch points in any potential operation targeting hardened nuclear or military infrastructure.