In a village close to a military site, residents report aerial vehicles hovering above their houses.

Small, unmanned craft were seen flying over four bases in England, the U.S. Air Force in Europe said. The Pentagon said that there had not been “any significant mission impact.”

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 British military has increased security around four air bases in the country that are used by U.S. forces after "a number" of drones were spotted near them.

LONDON - A criminal investigation has been launched after the U.S. Air Force reported that drones were spotted flying over English military bases, a British official said Wednesday. The U.S. Air Force reported several incursions occurred in the past week at four bases where the American forces operate.

Unidentified drones have been spotted again over three British air bases used by the U.S. Air Force, officials confirmed Tuesday. The three bases are all located within the same area of eastern England between Cambridge and Norwich,