When the US and Israel unleashed coordinated strikes on Iran, Keir Starmer initially held back on allowing the US to use UK military bases.

But then, on Sunday evening, the prime minister agreed that the US could use two of its military bases – but maintained that the UK did not believe in “regime change from the skies”.

Donald Trump said the “relationship is obviously not what it was”.

Why is this moment so challenging for Starmer?

“You have to understand how massively exposed Britain would be if the US decided one day you’re not our friend any more,” columnist Rafael Behr tells Helen Pidd. “Especially in the context of Brexit, how isolated, how actually dangerous to Britain that would be in a global context.”

“UK foreign policy has rested on an assumption that the relationship with Washington is the most important one. And, as a result, particularly in the sphere of defence and security, all the systems, the chains of command, everything are thoroughly enmeshed … there are keys and codes and switches that the Pentagon has that can turn off Britain’s safety in ways that the prime minister is extremely aware of, but doesn’t say it aloud.”

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