Trump's comments appear to confirm reports by US media that a new threat led to the bombers being removed after a major incident on 27 September when police were alerted to three "suspicious vehicles" near the airbase.

While speaking to a gaggle of reporters outside the White House, Trump was asked if a "specific threat" had led the US to pull its bombers from the airbase.

Trump replied: "Yeah I think we can say that. They didn't fly out by accident.

"There were some threats. And rather than tempting the enemy, we'll capture the enemy and beat the enemy. But why should we leave them there? So we moved them around a little bit. Not very far."

He added Washington "actually knows the people that made the threat", he but did not confirm who.

The exact nature of the threat that prompted the aircraft's removal from RAF Fairford remains unclear, but sources in Washington speculated to the BBC it might have revolved around sabotage attempts or attempts to strike the sensitive, expensive aircraft in the event of resumed hostilities with Iran.

One source close to the White House pointed to Ukraine's Operation Spiderweb - a covert drone attack on five Russian bases in June last year - as an example of what an enemy force could do, even at a distance.

"Whatever they thought it was, it was taken extremely seriously," the source said.

Trump's comments, and those of Vance before him, stand in stark contrast to those of Secretary of State Marco Rubio.

While both Trump and Vance pointed to an unspecified threat, Rubio was much more guarded in his language, noting that it was "not unusual" for military units and assets to rotate and be moved around the world.

RAF Fairford - in the Cotswolds in Gloucestershire - has been at the centre of an incident being investigated by counter-terror police.

Five men were initially arrested on suspicion of terror offences and subsequently released on bail. A sixth man, a UK-Iranian national, was also later arrested and released on bail.

Following the release of the first five men, Trump criticised the decision and US officials suggested Iran could have been involved in the incident.

Whitehall sources have not disputed that the decision from Washington to remove the bombers was in response to the incident at the airbase in Gloucestershire.

Speaking earlier on Monday, Rubio said he would not directly tie last week's incident to the decision to pull bombers from RAF Fairford.

He added: "It's not unusual to see movement of assets to different parts of the world based on exercises, redeployments, people changing out and new people coming in, new planes coming in and old planes going out."

Rubio said the US still had full confidence in the security of all its bases and that British authorities had been very co-operative since the incident.

Vance later said the bombers had been moved out of an "abundance of caution", adding Washington felt Iran was doing what it had "done for 49 years... which is engage in acts of terrorism against the US and against a lot of other people".

Days after the incident at RAF Fairford, Prime Minister Andy Burnham said there were "strong indications" that Iran had played a part in the incident but he did not provide further details, while Rubio said it had "clearly involve[d] the hands of a foreign actor" without going into further details.

Tehran has strongly denied any involvement.

In July, Iran said "any base used for aggression against Iranian territory constitutes a legitimate target for our forces".

RAF Fairford, near the village of Whelford, has been used as a forward operating location by the US air force for decades.

In recent months, the US has flown B-1 and B-52 bombers from the base for the Middle East, after the UK approved a US request to use it for defensive strikes on Iran.

The redeployment from RAF Fairford will reduce America's capacity to "quickly surge sorties against Iran, reducing the threat level somewhat", Christoph Bergs, research analyst at defence think tank the Royal United Services Institute told the Reuters news agency.

However, the use of the base had already been limited given London's stipulation that it should only be used for defensive strikes, he added.

The planes could potentially be sent to either Diego Garcia or bases in the Gulf to reduce the need for air-to-air refuelling but that would depend on capacity availability, negotiations with allies and security, Bergs added.