By Andreas Rinke and Rachel More
BERLIN (Reuters) - Drones were spotted flying over the U.S. air base at Ramstein in Germany in early December, a spokesperson for the U.S. Air Force said on Friday.
There were "no impacts to base residents, facilities, or assets," the spokesperson said. "In concert with host nation authorities, we continue to monitor the airspace to ensure safety and security of the community."
A security source told Reuters that German authorities had not traced the operators of the drones, but had ruled out the possibility that the drones were operated by amateurs.
The drone sightings over Ramstein were first reported by German news magazine Spiegel, which said a report by German security authorities had flagged a number of unexplained drone sightings over the base in the evening hours of Dec. 3 and 4.
Spiegel said drones were also sighted over locations belonging to German arms manufacturer Rheinmetall (ETR:RHMG) and chemicals group BASF.
"The safety of BASF sites is our top priority," a company spokesperson said in an emailed statement. "We therefore keep an eye on suspicious activities at all times and work closely with the relevant security authorities."
Rheinmetall, which is working with Ukraine and its European supporters to supply Kyiv with weapons, did not immediately respond to an emailed request for comment.
Drones have been spotted flying over strategically important facilities in Germany in recent months, including a liquefied natural gas (LNG) terminal in Brunsbuettel close to the North Sea. Prosecutors were investigating that incident on suspicion of "agent activity for sabotage purposes".
German intelligence chiefs have warned that the country's support for Ukraine in its war with Russia makes it a target for possible sabotage attempts, with recent security incidents at military barracks raising alarm further.