At least 10 US Air Force KC-135 refuelling aircraft departed RAF Mildenhall in Suffolk on Monday, according to flight-tracking data reviewed by BBC Verify.
The tankers left the Suffolk base and headed to other US facilities in Europe as well as Prestwick Airport in Ayrshire, Scotland.
Tracking via Flightradar24 showed two aircraft initially flying toward bases in Germany and Italy; one later returned briefly to Mildenhall before continuing to Spangdahlem in Germany, while the other flew circuits over Aviano in Italy before also landing at Spangdahlem.
Eight more KC-135s departed Mildenhall later the same day.
One aircraft that reached Prestwick belongs to the Nebraska Air National Guard and may have been on a routine transit stop.
The Wall Street Journal reported that the moves were made in response to a threat from Iran. The BBC has not independently verified that claim. The departures come weeks after the United States withdrew bombers from RAF Fairford in Gloucestershire following a suspected Iran-linked security incident. In September, a major incident was declared after three suspicious vans were spotted near Fairford; two British nationals later appeared in court in connection with an alleged plot, and eight men were arrested as part of a counter-terror investigation.
UK officials have stressed that bases remain secure. A Ministry of Defence spokesperson said the department does not routinely comment on other nations’ activity and that aircraft move regularly for operational reasons. Downing Street stated that protecting bases in the UK and overseas is a top priority and that the government works closely with police and allies. Education Secretary Lucy Powell said she could not comment on operational matters but added that security and safety of bases are taken “incredibly seriously.” A US Air Force spokesperson said aircraft rotate between locations for training and real-world requirements and declined further detail on operations-security grounds.
Former UK National Security Adviser Lord Ricketts noted that large tanker aircraft are prominent targets and that airbases have long perimeters, making them inherently vulnerable. He suggested the move may reflect an abundance of caution.
RAF Mildenhall, home to roughly 3,000 US military personnel and located about 80 miles north of London, is primarily used for refuelling and maintenance. It has previously supported Middle East operations. BBC observations indicated little aircraft movement at the base after the departures and no obvious additional visible security measures, with public viewing areas remaining open.