US Air Force says drones still being spotted over bases in England

Unidentified drones are still being spotted over United States Air Force (USAF) bases in England on Wednesday, a USAF spokesperson said, confirming that a fourth base had also been targeted by the week-long airspace incursions.

Since the first small unmanned aerial system was first spotted on Nov. 20, the number of drones has fluctuated and there have been a range of different sizes and configurations, said the U.S. Air Forces in Europe spokesperson.

The drones have also been seen over RAF Fairford, in western England, the spokesperson said, adding to the sightings reported on Tuesday over three bases in eastern England, RAF Lakenheath, RAF Mildenhall, and RAF Feltwell.

The drones have to date not impacted the bases, which are leased by the USAF from Britain.

"Our units continue to monitor the airspace and are working with host-nation authorities and mission partners to ensure the safety of base personnel, facilities and assets," the spokesperson said.

"We  do not discuss specific force protection measures, however we retain the right to protect our installations."

Britain said it was providing support to the U.S. Air Force response, with local media reporting 60 military personnel had been deployed to help investigate the issue.