US Air Force relocates aircraft from a base in England because of a threat, US official says

LONDON — The U.S. Air Force has relocated aircraft from a base in eastern England because of a threat, U.S. officials told The Associated Press.

The Military Air Tracking Alliance, a team of about 30 open-source analysts that routinely analyzes military and government flight activity, said that it spotted 13 U.S. aircraft stationed at RAF Mildenhall departing for bases in Scotland, Spain and Germany.

The Wall Street Journal, which first reported the evacuation, 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 another U.S.-run base in Britain, RAF Fairford, 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.

Some of the aircraft that were relocated were permanently based at RAF Mildenhall, while others were there on rotation and included a combination of Osprey aircraft and midair refueling tankers, the Military Air Tracking Alliance said.

The base also raised its alert level to FPCON Charlie — the second highest level — the organization said. That applies when an incident occurs or intelligence is received indicating that some form of terrorist action targeting personnel or facilities is likely.

The decision to move the aircraft was proactive rather than reactive, a U.S. official said, adding that the U.S. military is agile to potential threats. Some of the planes that left were in transit while others were permanently stationed at RAF Mildenhall and they may return, the official said. The official didn't elaborate on the nature and source of the threat.

U.S. Secretary of State Marco Rubio said that the United States is "constantly repositioning forces around the world for a variety of reasons," and referred questions to the Pentagon, which didn't provide immediate confirmation.

An official from the U.S. Air Force in Europe told the AP that the U.S. is "taking coordinated and appropriate actions" to ensure the safety and security of U.S. and U.K. personnel and their families. The official said that aircraft are rotated between bases for various reasons, including training and "real world requirements."

The official said that the U.S. military constantly assesses a variety of factors that determine what security measures are implemented. The official wouldn't provide further information on movement of assets or specific force protection for reasons of operational security.

Both officials spoke on condition of anonymity because they weren't authorized to speak publicly about sensitive military matters.

The U.K. prime minister's office said that British air bases are safe and their security is a top priority. The office said that the U.K. is in constant communication with the U.S., sharing intelligence and assessing threats together.

RAF Mildenhall, a U.K. base operated by the U.S. Air Force, hosts the 100th refueling wing, the only permanent refueling wing in the European region. It operates the KC-135 Stratotanker, a four-engine jet aircraft with a wingspan of 131 feet (40 meters) that can carry up to 83,000 pounds (nearly 38,000 kilograms) of cargo.

Five men were detained on Sept. 27 after three suspicious vans were spotted traveling toward RAF Fairford. The U.K.-owned base has been used by American bombers during decades of conflicts in the Middle East, including the Iran war.

Other arrests followed and two men have been charged under the National Security Act.

The U.K. Defense Ministry said in a statement that it doesn't comment on the activity of other nations and said aircraft and other assets move regularly according to operational requirements.