It has been the focus of international attention since events began unfolding near its perimeter in the early hours of Sunday morning, but why is the Gloucestershire base so important?

From its opening in 1944, through the Cold War and up to the present day, here is why this small piece of the Cotswolds has been so important to both the UK and US military., external

As Defence Secretary Wes Streeting told us yesterday, an investigation is under way into events at RAF Fairford since the early hours of Sunday.

He said he understood the frustration of the public in not knowing more - but pledged "as soon as we can keep the public informed, we will".

Here's what we do know this morning so far:

• Five men in their twenties, all UK nationals from London, who were arrested on suspicion of terror offences near the base were released on bail yesterday afternoon.
• Counter Terrorism Police say the men are "subject to stringent conditions on their movement and contact with others" and "absolutely remain under investigation as we explore multiple lines of inquiry".
• Residents evacuated from about 85 homes have been told they are able to return.
• A cordon remains in place today with vehicles entering through police checkpoints as security remains high.
• US Secretary of State Marco Rubio told a US TV channel what happened at RAF Fairford "clearly involves the hand of a foreign actor” and thanked British authorities for being "very co-operative and helpful" on "something that's a very serious incident."

US Secretary of State Marco Rubio said a television interview overnight that he believed the weekend incident at RAF Fairford "clearly involved the hands of a foreign actor".

He did not give any specific details to back up that assertion, but thanked the UK authorities for being "helpful".

Bea Swallow
Live page reporter

In the UK, if someone is arrested under the Terrorism Act, police can initially detain them for up to 48 hours without charge, and can apply for an extension for up to 14 days.

In this case, the men were arrested under the Police and Criminal Evidence Act which enables them to be bailed while investigations continue, and can be subject to "stringent" conditions.

Speaking to BBC Radio Wiltshire, former National Counter Terrorism co-ordinator Nick Aldworth says the decision to bail the five suspects after roughly 36 hours would not have been made lightly.

“I think people were probably expecting a different version of events," he acknowledges.

"But the conditions for applying bail to somebody are concrete, they’re not really discretionary. If somebody is entitled to bail, they will get bail. If they’re not, they won’t.

“I’m really comfortable that those decisions have been made with proper thought, and probably even more so, given the amount of international scrutiny around this."

Image source, Getty Images

While US President Trump has said the suspects were "under view for a long time", the BBC understands the operation was not "intelligence-led".

Speaking after the arrests on Sunday, Trump told reporters: "We had them under investigation. They were looking to ‌do big ⁠damage to our fort and working with the British worked out great."

Aldworth says he could not "square that circle", adding: "I certainly would never want to be the person to account for things said over the water".

Security remains high at RAF Fairford, with armed police at checkpoints talking to drivers and checking cars on approach roads.

Image source, PA Media

Image source, PA Media

Marie Lennon
Reporting from the scene

In the village of Fairford, people are trying their best to return to normal life following a surreal 48 hours - consisting of a major evacuation, the deployment of armed police, a 400m cordon and a bomb disposal robot.

Butcher Andrew Butler describes an air of uncertainty and paranoia among residents, as they discuss the latest developments in his shop.

"A lot of people are anxious about what’s been going on," he says.

"But then a lot of people are saying ‘well, you know, this is a consequence of living near an airbase', particularly one that is currently bombing another country."

Butler recalls an incident on Monday where a van, which had been parked "for quite a while", was suddenly swarmed by police and vehicles with flashing lights.

“Obviously somebody must have reported that van being there. That’s the situation now - people are worried, a bit panicky.

"Any suspicious vehicle that people aren't sure about, they think could potentially be a problem."

Despite all the closures outside RAF Fairford, there is still activity inside.

This B1-b Lancer bomber was photographed taking off from the base this morning.

Image source, Reuters

Inside the base, patrols are operating around the perimeter.

Fairford has played a key role in the ongoing conflict involving the USA, Israel and Iran.

Image source, Reuters

Fairford is not the only UK air base used by the United States Air Force.

Over in Suffolk in the East of England are Mildenhall and Lakenheath, where the state of alert has been increased by the US to "Charlie" - the second-highest alert level.

Charlie alert is usually an indication an incident has happened or intelligence suggests there could be a potential attack.

Lakenheath is home to fighter jets, while Mildenhall is mainly used as a base for refuelling tankers.

In his speech at the Labour Party conference on Monday, Defence Secretary Wes Streeting said he couldn't provide much further detail about the terror probe at RAF Fairford beyond what has already been reported.

Instead he praised the strength of the UK-US alliance.

"Our friendship with America is the closest alliance of any two nations on Earth, and we will always stand together against those who hate our freedom and those who wish us harm," he said.

"What we saw yesterday from our security services, our armed forces and our police was just a small glimpse of the extraordinary work they do every day."

Image source, Reuters

Over the past few days a large number of emergency personnel have been basing themselves at Fairford Town Football Club.

The scene there this morning is "very quiet", our photographer says.

Bea Swallow
Live page reporter

RAF Fairford is a military airfield located in the Gloucestershire Cotswolds, about four miles (6.4km) south of the town of Fairford.

It is owned by the UK's Ministry of Defence (MoD), but is operated on a day-to-day basis by the United States Air Force (USAF) under an agreement between the UK and US.

The site shares a long history with the American military, and has recently been used by US warplanes as a staging post for strikes on Iran due to its long runway, from which it can quickly deploy large bombers.

Historically, aircraft launched from the site have been involved in the Gulf War, the Kosovo War, and the Iraq War.

The rural area is typically quiet but about 170,000 people descend on the 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 war between the US, Israel and Iran.

Matty Edwards
Live page reporter

Here's some more from Whelford councillor Tristan Wilkinson, who has been speaking to BBC Radio Gloucestershire.

He is calling for RAF Fairford to communicate better and make it as easy as possible to report any concerns.

"The one thing I will be pressing the authorities for in the coming days is that we have a clear way of raising concerns, so that - god forbid if somebody sees some suspicious activity in the coming weeks - everyone knows the right number to call and that number will be answered quickly," he says.

Image source, Reuters

"We need to make sure the communities living next to these potential threats are well informed and involved in some of the decision making," he adds.

"I can understand why there isn't an ongoing dialogue with the base about their operational activity, but I do think there are things we could put in place that inform and reassure the local community about what is going on."

Wilkinson is also urging the wider community to show "tolerance" and "understanding" towards the evacuated residents as they deal with the disruption.

Matty Edwards
Live page reporter

It will take "a considerable amount of time" for life in the village of Whelford to return to normal, according to the local councillor for the area.

Councillor Tristan Wilkinson tells BBC Radio Gloucestershire that the mood among residents is a mixture of "confusion" and "weariness".

The vast majority of residents have now gone home, he says, but some who live near to the cordon around the white vans are subject to tighter restrictions.

"I don't think there's going to be anything normal about Whelford for quite a considerable amount of time," he says.

"Even when the police leave and they deem the area to be completely safe, as long as the conflict in the Middle East carries on, the people of Whelford and Kempsford are going to be living next to an operational base, so I think it's really important that the message of vigilance stays top of people's minds," he says.

"I think the mood is predominantly one of confusion, because obviously there are different stories emerging about what the nature of this was," he adds.

"People are really keen to understand what actually happened, who were these people and what was their intention."

He says after disruption and the small village becoming an international news story over the last two days "people just want to get on with their lives".

The cordon around the three vans has been in place since Sunday.

But some residents are beginning to enter and leave the cordon this morning on the western side.

Image source, PA Media

Yesterday Counter Terrorism Police gave more detail about the five men arrested near RAF Fairford on Sunday morning.

All five are UK nationals, it said: a 24-year-old from Camden, north London, three men aged 23, 24 and 25 from Westminster, and one aged 24 from Willesden, north-west London.

The head of UK Counter Terrorism Policing, assistant commissioner Laurence Taylor, said the men were released on bail under "stringent conditions" on Monday, but "absolutely remain under investigation as we explore multiple lines of inquiry".

He acknowledged speculation around the possibility of Iranian involvement, and said the force was keeping "an open mind in this investigation".

"But be assured, we are considering this from every possible angle, including that this may be actively committed by proxies or individuals either knowingly or unknowingly working on behalf of a foreign state," he said.

Iran's London embassy said it "categorically rejects and strongly condemns the recent unfounded and malicious speculations" of Iranian involvement.

Chris Phillips, the former head of the UK National Counter Terrorism Security Office tells BBC Radio 5 Live he does not believe police were fully aware of what was unfolding at RAF Fairford on Sunday.

He tells Naga Munchetty: "Police in this country don't allow terrorists to get hold of weapons and certainly they don't allow them to have van-fulls of explosives before they interdict, so I would have anticipated them having been arrested before that.

"Certainly historically we would have never allow that to happen. Historically they would have been stopped prior even to putting the explosives in any vehicle."

Naga asks: "So the intimation is they didn't know?"

Phillips responds: "I think so - I think that's probably the most likely scenario."

He adds that there are many possible explanations.

This story is only just beginningpublished at 08:10 BST

08:10 BST

Daniel Sandford
UK correspondent

Image source, Reuters

I think we are left reading the room because criminal proceedings are active, but one of the things we can say with some certainty is that there was some suspicion before the arrests on Sunday that that there might be some kind of plot to attack the base at RAF Fairford.

There were clear signs that security was being stepped up last week.

I think the question is now, given that Marco Rubio and Donald Trump are clearly hinting that this involved the hand of a foreign actor, what role did the men who were arrested in the early hours of Sunday play and to what extent were they aware of that?

Clearly the fact that they were released on bail yesterday shows there was not sufficient evidence at that point to hold them any further or to bring charges against them.

On the face of it, you have five men sitting in a village in three vans in the early hours of Sunday morning without any explosives, because that seems to have been the outcome of the tests done on the things found in the back of those vans.

We don't know what these men said to police in their interviews, but a key line of enquiry in the second phase of this investigation is whether there was some kind of controlling hand behind the activities and whether the people at the scene were really aware of they were involved in.

I think that's where this key phrase from the head of counter terrorism yesterday comes in, where he said his detectives are looking at this from "every possible angle", including that this activity might have been committed by individuals, knowingly or unknowingly working on behalf of a foreign state.

This is just the beginning of this investigation, not anywhere near the end.

The focus will be on trying to work out what led to those men being there, and if they were unknowingly caught up in something or whether they were there for perfectly innocent reasons.

That means means going through telephones, computers, searches at addresses - that is going to be the next stage of the investigation

Talking to military and police sources, I get the impression this is a story which is only just beginning - it is nowhere near being over.

A cordon is still in place around three vans which are being examined by counter-terrorism police.

While residents are being allowed back to their homes, there are still armed police stationed around RAF Fairford.

Image source, Reuters

Image source, Reuters

Image source, Reuters

Marie Lennon
Reporting from the scene

There is still a heavily guarded police cordon around the RAF base at Fairford.

The residents who live in the nearby village of Whelford have been told they can move home, but there is still hesitancy among them.

One local tells the BBC most have returned home, but police are telling them to stay inside and not take any photos.

"I haven’t gone home as I want to wait until I know more about what the hell happened, as it feels super dodge to me," she says.

Nick Johnson
Reporting from RAF Fairford

A cordon remains around the three vans which counter-terrorism police have been examining for possible explosive devices.

I am assuming that no viable explosives have yet been found.

The five men who were arrested on Sunday on suspicion of explosive and terrorism offences near the RAF Fairford military base have been released under investigation, subject to "stringent" bail conditions.

When people are detained under the terrorist act, they can be held for 14 days without charge.

The fact that these men were detained and then released on police bail after about 24 hours, suggests that police were pretty sure that other lines of inquiry needed to be followed.