Sirens sounded at several RAF bases on Friday evening amid reports of suspected drone activity.
Residents near RAF Mildenhall and RAF Lakenheath in Suffolk, along with those living close to RAF Feltwell in neighbouring Norfolk, reported hearing the alarms.
Locals said the noise resembled “war sirens” and began at about 5.30pm. An announcement delivered in an American accent reportedly followed over loudspeakers, instructing people to remain indoors and take shelter.
The incident came only days after the US military moved at least 12 aircraft from another RAF station because of a security threat connected to Iran.
Videos recorded by residents showed the sirens echoing across gardens in the darkness.
The US Air Force confirmed that the alarms at RAF Lakenheath were triggered by “suspected unauthorized drones”.
A spokesperson said: “This evening, USAF Security Forces personnel responded to suspected unauthorized drone activity over RAF Lakenheath.
“No personnel, aircraft or infrastructure were affected.
An American F-15 jet takes off from RAF Lakenheath in April 2018
A military vehicle at RAF Lakenheath on Tuesday
A light armoured vehicle and military personnel at the entrance to RAF Lakenheath on September 27
“We continue to work closely with our host nation counterparts to ensure the safety and security of our US service members, US and host nation civilians, contractors, and all of our families.”
The US Air Force urged anyone who noticed unusual or suspicious activity to report it to local authorities.
One resident near RAF Feltwell said she was “shaken up” when the sirens began in the afternoon.
“At around half 5 I was in my living room with my toddler and I heard what sounded like war sirens,” Nicole Barraclough, 22, told Our News Outlet.
“At first I thought it was a car playing weird music past my house. Unfortunately, the sound continued. It went on for five minutes.
“We thought maybe it was a drill. Then we heard an American male voice from the speakers telling people to remain indoors and shelter.”
Local MP Nick Timothy said he had contacted officials at RAF Lakenheath after speculation about the incident. He was told there was “no threat to the public” and that the situation had been resolved.
In a social media post, the Conservative MP for West Suffolk encouraged residents to keep reporting anything suspicious or unusual to the authorities amid the heightened security situation.
He also called on the Ministry of Defence and the US Air Force to provide as much information as operational security allowed.
The latest incident follows the recent movement of US military aircraft from RAF bases.
On November 9, nine US Air Force refuelling aircraft were moved from RAF Mildenhall to bases elsewhere in the UK, Germany and Spain.
Three V-22 Ospreys, which are used by American special forces, were also transferred to neighbouring RAF Lakenheath, where they can be kept in fortified hangars.
A former RAF chief described the sudden relocation as “extraordinarily unusual”. It followed a similar withdrawal of bombers from RAF Fairford in Gloucestershire last month after an alleged Iranian terror plot was foiled.
The precise nature of the latest threat remains unclear and is being assessed by US officials, according to the Wall Street Journal.
RAF Lakenheath issued a drone warning last week, asking local residents and people living on the base to report sightings “immediately” to security personnel or police.
RAF Mildenhall and RAF Lakenheath later raised their security status to “Force Protection Condition Charlie”, the second-highest threat level. The designation is used when intelligence indicates that a terrorist attack is likely.
