The United States military moved its aircraft out of RAF Mildenhall in Suffolk, England, on Monday after a reported threat linked to Iran, in the second such withdrawal from a British air base in a matter of weeks. The Wall Street Journal reported that two US refuelling tankers based at Mildenhall were diverted to Germany on Monday morning, and several more tankers were moved to Germany and other locations later in the day.

Source: Wall Street Journal via Reuters

Flight-tracking data reported by Sky News showed nine tankers and three Osprey aircraft leaving Mildenhall late on Monday afternoon and into the evening. All nine tankers are Boeing KC-135 Stratotankers; most went to air bases in Germany and Spain, one is now at RAF Prestwick in Scotland, and the three Ospreys moved to nearby RAF Lakenheath in Suffolk.

Source: Sky News

Security raised to FPCON Charlie at two bases

The United States also raised the security posture at both RAF Mildenhall and RAF Lakenheath to Force Protection Condition (FPCON) Charlie, the Wall Street Journal reported, citing a US official familiar with the matter. FPCON Charlie is the second-highest level in the US military's force-protection system and applies when intelligence indicates that some form of terrorist action is likely. A US official separately confirmed to The War Zone that protection had been stepped up at both bases, without saying what had prompted it.

Source: The War Zone

The exact nature of the reported threat is not yet known, and US officials are still discussing it, the Journal said. Britain's Ministry of Defence declined to discuss the movements. A spokesperson said: "We do not routinely comment on the activity of other nations. Aircraft and other assets move regularly according to operational requirements." Cabinet minister Lucy Powell told Sky News the security of military bases in the UK was kept under review.

Second British base cleared in weeks

The move comes weeks after the United States withdrew its bombers from RAF Fairford in Gloucestershire following a suspected Iran-linked security incident near that base. US officials have not publicly confirmed that the Mildenhall move is directly connected to the Fairford investigation. Mildenhall is one of the US Air Force's key bases in Europe: it hosts the 100th Air Refueling Wing, whose KC-135 Stratotankers refuel US and allied aircraft in flight.

The departures also came as US refuelling tankers and other aircraft continue to flow towards the Middle East while President Donald Trump weighs whether to resume strikes on Iran. On Monday Trump said further US military action against Iran did not currently seem necessary and that he planned to hold off on new strikes for now, after appeals from Gulf states including Qatar — a position Tehran has not publicly accepted, and one that has not stopped precautionary moves like the Mildenhall dispersal.