A little over a month after the U.S. Air Force suddenly evacuated a dozen B-1 bombers from RAF Fairford, an air base in southern England, the U.S. has now evacuated aircraft from another base, RAF Mildenhall, also allegedly due to an unspecified threat. According to The Wall Street Journal, two U.S. air refueling tankers that were using Mildenhall left for Germany earlier in the morning on Monday, while several other tankers at the base were moved to Germany and other locations later in the day, according to flight-tracking data and an unnamed official “familiar with the matter.”

RAF Mildenhall, located in Suffolk, England, is home to the 100th Air Refueling Wing.