The US Embassy in the UK on Sunday urged American citizens to "exercise caution" after five men were arrested on suspicion of preparing a terrorist act near RAF Fairford in Gloucestershire. In a statement, the embassy said it was aware of the arrests and advised US citizens to be mindful of their personal security and follow instructions from local authorities.
The warning came after police responded to reports of suspicious activity near the air base, which is used by the US Air Force for operations from Europe.
US President Donald Trump praised the British police response, saying the suspects had been under investigation and were "looking to do big damage" to the US facility.
"It was fantastic. Working with Britain, it was an amazing job. We had them under investigation. They were looking to do big damage to our fort, and working with the British worked out great," he told reporters in Illinois.
Trump added: "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."
Farmer Raises Alarm
The arrests followed a report from a local resident who encountered three white vans and a group of men near the air base. The woman told the Telegraph she had been returning from a party when she saw the vehicles blocking a road.
"I just thought what the hell are they doing… I saw a group of Middle Eastern-looking young guys running off through the trees. Some of them had masks or balaclavas on, and they all scattered ahead of us as we drove back past," she said.
"Some of them ran into the fields, and some of them turned to run towards the air base. We realised this was something pretty serious," she added.
The resident is understood to have called 999 at about 00:45 to report men acting suspiciously near the vans. Police said viable incendiary devices and chemicals were found inside one of the vehicles.
About 85 homes near RAF Fairford were evacuated while armed police and specialist bomb disposal teams searched the area.
A local resident, Julian Tudsbery, said the woman had initially tried to contact police at the air base. "Evidently, they phoned the airbase police, who didn't answer the phone," he said. "It just rang out so she dialled 999."
What We Know About the Incident
Maggie Blyth, Temporary Chief Constable for Gloucestershire Police, said the situation was now believed to be "contained".
"These arrests will no doubt have caused some shock and anxiety and we want those living locally to RAF Fairford and across Gloucestershire to be sure and to know that, as agencies, we are working closely together to support them," she said. "You will appreciate this is a fast-moving situation and all agencies across Gloucestershire are actively working to respond to our communities' needs and continue to provide information to our communities on a regular basis, we will also continue to assist counter-terrorism policing with their investigation and liaise with other national partners."
"I can give reassurance that we believe the matter to be contained and as a set of agencies working together across Gloucestershire, we are gathering and responding to local intelligence all the time," she added.
Police have not said that the arrests were part of a pre-planned operation, and the investigation remains ongoing.
Prime Minister Andy Burnham said the government would "always take every step necessary" to protect the country. "The investigation remains ongoing, and I would urge people not to speculate while the authorities establish the full facts," he said.
Security Tightened at US Bases
RAF Fairford has been placed on Delta alert, described as the highest threat level used by the US Department of Defense.
Security has also been tightened at other US bases in the UK. Reports said RAF Lakenheath in Suffolk had been placed on Charlie alert, the second-highest level.
A spokesman for the 48th Fighter Wing said: "We constantly assess a variety of factors that determine what measures are implemented or modified." "Please be assured that the Tri-Base area (RAF Lakenheath, RAF Mildenhall, and RAF Feltwell) remains vigilant and will take appropriate action to ensure the safety and security of US service members, US and UK civilians, contractors, and their families," the spokesman added.
RAF Fairford has been used for US military operations, including strikes against Iran. Iran's Revolutionary Guard warned in July that Britain should not allow US bombers to operate from the base.
In June, the US government announced plans to spend about $500m (£377m) on expansion and military infrastructure at RAF Fairford.
The Royal International Air Tattoo at the base was also cancelled earlier this year after organisers cited the "escalating geopolitical situation in the Middle East" and the need for the British and US air forces to maintain "unrestricted, 24/7 operational readiness at the base".