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 from there 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.
Source: www.bbc.co.uk
