An American official says the U.S. Air Force has relocated aircraft from a base in eastern England because of a threat. The Military Air Tracking Alliance said that it spotted 13 U.S. aircraft stationed at RAF Mildenhall departing for bases in Scotland, Spain and Germany. The Wall Street Journal first reported the evacuation on Tuesday and said that the threat related to Iran. The report cited “people familiar with the matter.” The relocation of the aircraft came less than two months after the U.S. Air Force withdrew its bombers from the U.S.-run RAF Fairford base in England as police investigated a suspected terror plot linked to Iran. Bombers flying out of RAF Fairford had been used to strike Iran during the Middle East conflict.