Military personnel are shown loading a US Air Force plane at RAF Mildenhall on Tuesday afternoon

More than 12 US Air Force aircraft have left a second airbase in Britain weeks after the US withdrew its bombers from RAF Fairford over a suspected Iran-linked security incident.

The latest plane to leave, a Boeing Stratotanker KC-135 refuelling aircraft, flew from RAF Mildenhall in Suffolk on Tuesday afternoon and headed towards Germany.

The Wall Street Journal reported that the departures have been in response to a further threat from Iran but the BBC has not independently verified that claim.

Downing Street has insisted British air bases are safe and that their security is a "top priority".

US military aircraft were pictured at Prestwick Airport, near Glasgow

Using public flight-tracking site Flightradar24 BBC Verify was able to see 10 USAF KC-135 tankers leaving RAF Mildenhall throughout Monday.

Two aircraft which left the base on Monday morning initially flew to US bases in Germany and Italy.

The first of these KC-135s flew to Spangdahlem air base in south-west Germany where it completed a series of circuits before returning to Mildenhall. It then flew east and landed at Spangdahlem.

The other aircraft was seen flying circuits over Aviano air base in north-east Italy before going on to land at Spangdahlem. Neither aircraft was tracked returning to Mildenhall.

Later in the day more KC-135s flew from Mildenhall - two flew to Spangdahlem, one to the US base at Ramstein in Germany and four to Morón air base in southern Spain. Three Osprey aircraft have have also left that RAF base.

One aircraft, belonging to the Nebraska Air National Guard in the US, went to Prestwick Airport in Ayrshire. It is not clear if this was a planned stopover before the jet returned to its home base.

Asked about Monday's flights, a Ministry of Defence (MoD) spokesperson told the BBC: "We do not routinely comment on the activity of other nations. Aircraft and other assets move regularly ​according to operational ​requirements."

Downing Street, meanwhile, has insisted that UK airbases are safe, with the prime minister's official spokesperson saying "the protection of our bases, both in the UK and across the world, is a top priority".

About 3,000 military personnel are stationed at RAF Mildenhall, which is around 80 miles (130km) north of London.

There was no apparent additional security at the base on Tuesday, and the spaces from which the public could photograph aircraft remained open.

The base is mostly used for refuelling and maintenance operations.

Flights carrying US presidents, including Donald Trump, have often used it, and Trump came through RAF Mildenhall on his way back to the US from a Nato summit in Ankara in July.

US President Donald Trump at RAF Mildenhall in July after a Nato summit in Turkey

It has also been used as a staging area for aircraft and material bound for the Middle East, with air refuelling tankers "forward deployed" to the region during operations against Iran.

Asked about the US evacuating aircraft from RAF Mildenhall, Education Secretary Lucy Powell told BBC Breakfast she could not comment on ongoing operational matters.

She added that "we take the security and safety of our bases incredibly seriously" and "we will always act on security intelligence when we need to".

A US Air Force spokesperson said its aircraft "rotate between installations and operating locations for a variety of reasons including training and real world requirements".

"US military aircraft are hosted in accordance with access, basing, and overflight agreements with our allies and partners. Due to operations security, we will not provide further information on movement of assets," the spokesperson added.

Former UK national security adviser Lord Ricketts told BBC Radio 4's Today programme: "We are talking about an airbase which houses these large tanker aircraft. Of course, they are large targets, an airbase has a long perimeter, so they are inevitably vulnerable."

He added: "Nobody knows at this stage what this information was. I suspect part of it is an abundance of caution."

Aircraft left RAF Mildenhall in Suffolk and landed at other American bases in Europe and also at Prestwick Airport in Ayrshire

Retired Royal Air Force Air Marshal Greg Bagwell told BBC Verify "we need to keep an open mind" about the reasons behind the US aircraft movements.

He suggested they could be the result of an exercise, or because the weather forecast meant it was safer to move the aircraft to other bases ahead of planned deployments elsewhere.

Bagwell said the decision may also have been taken because of a hoax as part of "nuisance hybrid warfare" by countries like Iran - or it could be a genuine threat.

He said the aircraft being dispersed to several bases could indicate the US was spreading them around to keep them safe and the moves have been "triggered by something".

Bagwell added that the reason "we haven't seen an attack succeed or even happen" could be that "maybe our intelligence and our security is better than people might believe".

Monday's departures from Mildenhall follow a security incident at RAF Fairford, a US-operated airbase in Gloucestershire.

A major incident was declared after three suspicious vans were seen near that base in September. It later emerged that the US had pulled its bombers out of the base and returned them to America.

Two British nationals appeared in court in October in connection with an alleged Iran-linked plot.

Seven men have been arrested as part of the investigation, Counter Terrorism Policing confirmed to the BBC on Tuesday, while an eighth has been interviewed under caution and since charged under Section 3 of the National Security Act 2023.

Iran has previously said that it considered UK bases used by the US for military strikes to be "legitimate targets".

Additional reporting by Nick Johnson at RAF Mildenhall, and Rob Corp, BBC Verify.

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