A suspected terror plot against an RAF base used by the US Air Force (USAF) was “looking to do big damage”, US President Donald Trump has said.

Five men have been arrested on suspicion of explosive and terrorism offences after armed police stopped three vans in the early hours of Sunday.

The police operation near the village of Whelford in Gloucestershire was not intelligence-led – meaning investigators had not known about any potential plot in advance, the Press Association understands.

However, Mr Trump praised the UK police response and suggested authorities already had the suspects under investigation.

Using the American term for military sites – fort – to refer to RAF Fairford, which hosts USAF heavy bombers, he told reporters in the US: “It was fantastic. Working with Britain, it was an amazing job.

“We had them under investigation. They, they were looking to do big damage to our fort, and working with the British worked out great.

“It may have been Scotland Yard, I don’t know. We worked with a lot of them.

“We had them under view for a long time, and we got them. Thank you.”

Three “suspicious vehicles” travelling towards RAF Fairford in Gloucestershire were reported to police at about 12.45am on Sunday.

The men were arrested by armed officers in the Whelford area under suspicion of committing offences under the Explosives Act.

They were then further arrested under suspicion of preparation of a terrorist act.

A resident of Whelford told PA she called police after she saw three vans “blocking the road”, before spotting a “large group of hooded and ‘balaclava’d’ men”.

The resident, who asked not to be identified, said she was driving home in the early hours of Sunday morning when she saw 10 people in the road.

She said the RAF Fairford base was known by residents to be on lockdown due to a “terror threat”.

The resident called 999 after discovering the men and said police arrived on the scene around 15 minutes later.

“They would have seen the bright headlights,” she said.

“They probably thought we were the police (and) panicked.”

She added: “It would appear that by doing so I just derailed whatever they were planning.

“A plucky amateur shouldn’t be spotting an unusual bit of activity at 1am when the air base is on high alert.

“I think it’s absolutely astonishing.”

About 85 households have been evacuated from their homes near RAF Fairford and a major incident was declared by police within a 400-metre cordon.

Aerial footage showed a bomb disposal robot inspecting three white vans, two of which had open rear doors. Large black barrels appeared to be scattered around.

Prime Minister Andy Burnham said the incident was “deeply concerning” and the Government will “always take every step necessary” to protect people.

And Defence Secretary Wes Streeting said he would not comment on a live operation but he had been in contact with Pete Hegseth, his opposite number in the US.

Speaking at a fringe event at Labour conference, he said: “I don’t think it will come as a surprise to anyone that, given the importance of Fairford, not just to the United Kingdom but to the United States, we’ve been working closely with our American friends, and I’ve been in touch during the course of today with my counterpart Pete Hegseth.”

Asked if there was any Iranian involvement, he said: “I’m not going to comment on the underlying motivations of those who’ve been arrested today, or indeed the, sort of, the genesis of their activity, I think it’s far too early to comment or speculate, and it would be irresponsible for me to do so.”

In March this year, after then prime minister Sir Keir Starmer granted permission for “defensive” US action against Iranian missile sites from UK bases, four American bombers landed at RAF Fairford and the US started using British bases for “specific defensive operations”.

Evacuated villagers may have to stay overnight while crews make the scene safe, Gloucestershire County Councillor Paul Hodgkinson confirmed to PA, calling the incident “destabilising”.

Julian Tudsbery, who has lived in Whelford for 30 years, said a resident had reported three “suspicious vans” in the village in the early hours of Sunday.

“Evidently, they phoned the airbase police, who didn’t answer the phone,” he said. “It just rang out so she dialled 999.”

He said he was evacuated at around 7am, adding: “(The police) were then banging on the door, so I went downstairs in my dressing gown.

“There were several police, three police cars in the drive, and they said you need to evacuate, there’s been a major incident, said he couldn’t elaborate.”

Meanwhile a woman living on the base’s perimeter described an apparent increase in military security in recent days.

The woman, who asked not to be identified, told PA: “In the prior few weeks they have put heavy, very heavy, vehicles across all gates.”

She described them as “very big tractors and things like that” parked behind crash-gates into the base, adding: “Obviously they’re taking security seriously.”

The resident, who has lived there for about 50 years, also said “great big concrete walls” have been placed behind some gates, including on Dunfield Loop and Whelford Road.

Counter Terrorism Policing senior national co-ordinator, Deputy Assistant Commissioner Vicki Evans, said: “We are in the early stages of an investigation and five men remain in custody.

“As you would expect, we are working closely with our partners to understand the circumstances of the incident.

“We continue to work with Gloucestershire Police to keep the community safe as we work to gather evidence from the scene.”

Suspects arrested under the Terrorism Act 2000 can be detained for up to 14 days without charge, compared to the 24-hour limit for standard arrests without an extension application.

The arrests come amid heightened concerns around the threat from hostile states to the UK, with Russia and Iran among those that have used proxies to commit crimes on their behalf on British soil.

In March, officials said the number of national security cases involving activity by hostile states including Iran increased 50% in the six months to December 2025.

A recent spate of antisemitic attacks on Jewish sites in London this year were claimed by a group called Harakat Ashab al-Yamin al-Islamia, the Islamic Movement of the Companions of the Right (Hayi), which is thought to be backed by Iran.

Support for Iran’s Islamic Revolutionary Guard Corps (IRGC) and Hayi were later banned in July by Sir Keir.

Under the state threat powers, anyone supporting or assisting the groups will face a maximum punishment of 14 years in prison, but ministers will need parliamentary approval first.

The Fairford incident also comes amid an ongoing war between the US and Iran.

Investigators will be working to analyse any devices seized from those arrested to establish details of any plot and any potential motivation.

RAF Lakenheath in Suffolk confirmed it is on Charlie alert, which is the second-highest threat level that can be issued by the US Department of Defence.

The confirmation to PA came amid reports that RAF Fairford has been raised to the highest threat level, Delta.

A spokesperson for the USAF said its personnel based at RAF Fairford “remain vigilant”, but “for operational security reasons we will not discuss specific force protection measures”.

They said its 501st Combat Support Wing and UK counterparts “will take appropriate actions to ensure the safety and security of our US service members, civilians, contractors, and their families”.

The 501st is “the only combat support wing in the USAF” and operates from 10 bases including Fairford, according to its website.