The U.S. Air Force abruptly relocated more than a dozen aircraft from RAF Mildenhall in eastern England amid an emerging security threat, U.S. officials confirmed Tuesday.The Wall Street Journal first reported the move, citing sources who said the threat originated in Iran.As U.S. officials assessed the threat’s nature and urgency, commanders raised the base’s security level to Force Protection Condition Charlie, the military’s second-highest alert level, indicating a likely terrorist threat against personnel or facilities.IRAN HAS ‘SUBSTANTIALLY INCREASED’ EFFORTS TO TARGET AMERICANS ABROAD, US INTELLIGENCE MEMO WARNSFlight-tracking data and open-source analysts with the Military Air Tracking Alliance identified 13 U.S. aircraft leaving the base late Monday, the Associated Press said.Nine Boeing KC-135 Stratotankers were moved to airfields in Scotland, Germany and Spain.Three CV-22B Ospreys were relocated to nearby RAF Lakenheath, which has hardened aircraft shelters.A U.S. official told The Associated Press the moves were precautionary, noting that some aircraft were on rotational deployments while others were permanently stationed in the United Kingdom.IRAN UNDER SCRUTINY AFTER PLOT FOILED NEAR UK BASE USED BY US MILITARYThe move marks the second major relocation of U.S. military aircraft from Britain in less than two months.In early October, the Air Force pulled heavy bombers from RAF Fairford in Gloucestershire after British counterterrorism police stopped three suspicious vans headed toward the base Sept. 27.Two men have since been charged under the United Kingdom’s National Security Act.Separately, the Justice Department unsealed indictments against three Iranian-backed operatives on Tuesday accused of involvement in coordinated terrorist plots across Europe, including RAF Fairford.UK POLICE ARREST ‘EXPLOSIVE’ SUSPECTS NEAR US AIRBASE, KEY TO IRAN WARRAF Mildenhall is home to the 100th Air Refueling Wing, the only permanently based U.S. tanker wing in Europe.Its KC-135 Stratotankers support allied aerial refueling and long-range strike missions across the region.Secretary of State Marco Rubio said Tuesday that Washington routinely repositions military forces.”We are constantly repositioning forces around the world for a variety of reasons,” Rubio told reporters when asked about the evacuation.A 10 Downing Street spokesperson said British air bases remain secure and that London and Washington continuously share intelligence on potential threats.