1. What happened

At around 00:45 on Sunday 27 September, police received a call about three suspicious vehicles travelling towards RAF Fairford in Gloucestershire, Assistant Chief Constable Richard Ocone said. Armed officers arrested five men in the nearby village of Whelford, first on suspicion of offences under the Explosives Act. Counter Terrorism Policing confirmed they were also arrested on suspicion of preparing a terrorist act.

A 400-metre cordon was set up while the Army's explosive ordnance disposal unit examined the vehicles, and about 85 households were advised to evacuate. Helicopter footage showed a bomb disposal robot moving between three white vans; police have not confirmed which vehicles were examined. On Sunday evening, CNN teams near the perimeter heard what sounded like two controlled detonations.

"We are in the early stages of an investigation, and five men remain in custody," said Vicki Evans, Deputy Assistant Commissioner and senior national coordinator for counter-terrorism policing.

2. Why the base matters

RAF Fairford hosts the headquarters of the US Air Force's 501st Combat Support Wing. Since February it has been a key hub for American operations against Iran, including B-1 and B-52 bombers, under British authorisation limited to defensive purposes such as strikes on Iranian missile sites. A US Air Force spokesperson at Fairford said that, for operational security reasons, it would not discuss specific force protection measures.

Tehran has named the base before. In July, after a B-1 bomber flew a strike mission from Fairford, Iran's Revolutionary Guards declared that "any base used for aggression against Iranian territory is a legitimate target for us". The British government replied that the country stood ready "24/7" to defend itself.

3. Two versions, and what to watch

Donald Trump said the US and the UK had had the men "under view for a long time". ITV News and GB News report the opposite: the operation was not intelligence-led, and a resident told the BBC that villagers reported the vans as soon as they arrived. ITV also reports that one line of inquiry is whether representatives of the Iranian regime paid others to carry out the plot. Police have confirmed no link to Iran, and have not confirmed that the base was the target.

Prime Minister Andy Burnham said the government will "always take every step necessary" to protect the country; Defence Secretary Wes Streeting said he had spoken to his US counterpart, Pete Hegseth. The US Embassy in London advised Americans to be mindful of personal security.