The Royal Air Force Lakenheath base houses the USAF’s 48th Fighter Wing.
London CNN  — 

Unidentified drones have been spotted flying over three bases used by the United States Air Force in Britain, the two countries have confirmed.

The objects were seen between Wednesday and Saturday flying over the Royal Air Force’s Lakenheath, Mildenhall and Feltwell bases, all used by the US Air Force (USAF).

“The number of (unmanned aircraft systems) fluctuated and they ranged in size/configuration,” a spokesperson for the US Air Forces in Europe said in a statement.

“Installation leaders determined that none of the incursions impacted base residents or critical infrastructure,” the spokesperson added.

A spokesperson for Britain’s Ministry of Defence said: “We take threats seriously and maintain robust measures at defence sites. This includes counter-drone security capabilities.”

Both nations said they would not comment further.

The three bases are located within a few miles of each other in eastern England. Since 1992, Mildenhall has been home to the only permanent American wing in Europe that conducts air refueling operations, while Lakenheath houses the USAF’s 48th Fighter Wing, which has played a role in post-9/11 operations in Afghanistan and Iraq.

In 2017, a car attempted to ram the entrance to the Mildenhall base, resulting in shots being fired by US personnel and the base being briefly locked down.

CNN’s Paradise Afshar contributed reporting.