US Secretary of State Marco Rubio says the weekend incident at RAF Fairford "clearly involves the hands of a foreign actor"
Speaking to US media, he doesn't give further details but thanks UK authorities for being "co-operative" and "helpful"
Five men arrested on suspicion of terror offences near the base, which is used by the US military, were released on bail on Monday - here's what else we know
The men - all UK nationals in their 20s who live in London - had been arrested under the Explosives Act and on suspicion of preparing a terrorist act
AC Laurence Taylor, the head of UK counter terrorism policing, has said officers are pursuing multiple lines of inquiry, including if proxies working on behalf of a foreign state could've been involved - the Iranian embassy in the UK denies involvement
Residents from 85 households evacuated on Sunday have started returning home. With a cordon still in place and roads blocked, they want to know how long the disruption will last, writes our reporter
Leigh Boobyer
Live page reporter
Gloucestershire Police has confirmed a statement will be read to the media at 12:45 BST in relation to the major incident.
It will be delivered by a senior officer who will not be answering questions after the briefing.
Image source, Getty ImagesRAF Lakenheath is home to the US Air Forces' 48th Fighter Wing
The US Department of Defense has raised the threat level at RAF Lakenheath in Suffolk - which hosts the US Air Force's 48th Fighter Wing - following the incident near RAF Fairford.
RAF Lakenheath confirmed that the base is on Charlie alert, the second-highest threat level that can be issued by the US DoD.
It follows reports that RAF Fairford has been raised to the highest threat level, Delta
The US government says threat level Charlie applies when "an incident occurs or intelligence is received indicating some form of terrorist action targeting personnel or facilities is likely”.
While it says Delta applies "in the immediate area where a terrorist attack has occurred or when intelligence has been received that terrorist action against a specific location or person is imminent".
Nick Johnson
BBC News
Image source, PA MediaI spent a number of days around RAF Fairford as US bombers and military equipment arrived at the beginning of March, following US strikes on Iran.
Impressive military machinery was taking off and landing with frequency - providing an accessible spectacle for aviation enthusiasts.
I was struck by how close the public could get to the large perimeter fence - just beyond which the US Air Force's B-1 bombers were positioned.
While police officers made occasional security checks and ensured parked cars were not blocking roads or homes, there were many hundreds of people who were easily able to gather at the perimeter fences.
We do not yet know the nature of this incident but it may prompt a rethink regarding how close cars and people are able to get to the airfield itself.
Jack Grey
Live reporter
Image source, PA MediaArrests have been made and a major incident declared following an incident near RAF Fairford in Gloucestershire.
Here's what we know:
What we don't yet know:
Sammy Jenkins
BBC News, Live page reporter
The Royal Air Force Station is located in the Cotswolds about four miles (6.4km) south of the town of Fairford, which sits along the River Coln.
The area is typically quiet but about 170,000 people descend on the RAF site every July for the Royal International Air Tattoo, the largest military show in the world.
The event was cancelled this year due to the conflict in the Middle East.
Annabelle Martin
Reporter
I'm at the the leisure centre where residents have been placed after being ordered to leave their homes during the middle of the night.
Families are gathered in a café area, anxiously checking their phones and asking for updates. About 30 people are here, including children and elderly people, with some still in their pyjamas.
Leigh Boobyer
Live page reporter
Prime Minister Andy Burnham is receiving updates on the incident near RAF Fairford.
A government spokesperson said: “We are grateful to the emergency services, who have acted quickly to detain several suspects and put measures in place to keep the community safe.
“It would be inappropriate to comment further whilst investigations are ongoing.”
Alastair McKee
Reporting from the scene
I'm at the scene near RAF Fairford, where cyclists and drivers are being turned around by police near the cordon.
The cordon is a substantial way out of the village, beyond the sight of homes.
I'm stood by the RAF base, and I can see through the fence the B-1B Lancer bombers used by the USAF.
Police are in full gear and armed.
Frank Gardner
Security correspondent
Whitehall officials say the investigation into the incident at RAF Fairford is being led by counter-terror police. The BBC understands that it was not intelligence-led.
Image source, PA MediaDefence Secretary Wes Streeting has thanked emergency crews for their "swift" response to the incident near RAF Fairford.
"We can be reassured that this is being dealt with and it is exactly why our emergency response teams and Armed Forces are on standby 24/7," he writes on X.
Leigh Boobyer
Live page reporter
Speaking to the BBC, Cotswold district councillor Tristan Wilkinson urged people to "remain calm".
"It's new so we need to keep speculation to a bare minimum.
"All I ask is people stay away from the area. This is a serious incident," he added.
Image source, ReutersArmed police are at the scene
Describing the scenes near RAF Fairford as "worrying", South Cotswolds MP Roz Savage said on X: “I have contacted the police for further updates and I’ve been told that it is believed the incident is contained.
“I would like to thank them for the work they are currently doing."
A spokesperson for the US Air Force said its personnel based at RAF Fairford "remain vigilant".
They added that while they were aware of the current situation at Fairford, they would not discuss specific force protection measures.
"The 501st Combat Support Wing and our fellow UK-based Wings remain vigilant and will take appropriate actions to ensure the safety and security of our US service members, civilians, contractors, and their families," the spokesperson said.
"We constantly assess a variety of factors that determine what measures we institute or modify to protect our installations, our people and their families."
Britain said in July its armed forces were ready to protect the country from any attack after Iran's Revolutionary Guards issued a warning not to allow US bombers to fly from Fairford.
The Fairford site has been used since February to launch operations against Iran during the Middle East conflict.
Residents in the village of Whelford have been evacuated and taken to a leisure centre while investigations continue.
Frank Gardner
Security correspondent
For an official account of what has happened at RAF Fairford, we will need to wait for a police statement. But the context for this is troubling.
It comes amid a rising number of incidents across Europe of what’s termed "hybrid warfare", allegedly being orchestrated by the Kremlin, or more specifically its GRU military intelligence, as punishment for those countries supporting Ukraine.
These incidents include arson, cyber attacks, overflights by unidentified drones close to sensitive locations like nuclear bases and power stations and most recently the discovery of three explosive drones at Leipzig-Halle airport in Germany which serves as a cargo hub for resupplying Ukraine.
Russia’s view is that Nato, and some countries in particular, like Britain, are already waging an indirect war with Moscow by supplying Ukraine with long-range munitions and that it is time for these countries to "feel some pain".
At the same time, it’s worth bearing in mind that US warplanes have been using British bases as staging posts in the US war on Iran.
Right now though, Iran is pushing for a peace deal, albeit on terms unacceptable to Donald Trump.
Leigh Boobyer
Live page reporter
Police say the Army's specialist explosive ordnance disposal team is currently examining a number of vehicles in the village of Whelford.
Image source, ReutersHomes in the village of Whelford have been evacuated with residents taken to a nearby leisure centre
Image source, ReutersPolice say 'several men' were arrested under the Explosives Act
Image source, ReutersRoad blocks and armed police are in place in the Cotswolds village
Image source, ReutersEmergency vehicles are in place throughout the village
Leigh Boobyer
Live page reporter
Since it opened in January 1944, RAF Fairford has been used for various reasons.
The United States Air Force (USAF) 501st Combat Support Wing manages and supports operations and the site is predominantly used by USAF heavy bombers like the B-1B Lancer, the B-2A Spirit and the B-52H Stratofortress.
It also routinely supports Bomber Task Force operations.
The base has been recently used to deploy American bombers since the country's conflict in Iran began on 28 February.
Then, in March, after the 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 began using British bases for "specific defensive operations".
Image source, ReutersA major incident has been declared near RAF Fairford, Gloucestershire, and several men arrested on suspicion of explosives offences, police say.
Residents in Whelford, a nearby village, have been evacuated and taken to a leisure centre while investigations continue.
A cordon is currently in place in the area and officers say they believe the incident is contained