The German government announced Friday that unidentified drones had been flying over sensitive military and commercial sites.
Among the sites is the US air base in Ramstein, in the western state of Rhineland-Palatinate.
The sightings were first reported through the German magazine Der Spiegel.
It cited a report from German security authorities saying that several drone sightings were registered over the Ramstein base late on December 3 and 4.
Der Spiegel said that unidentified drones were also sighted over facilities belonging to German arms maker Rheinmetall.
Unidentified drones were also seen over the Brunsbüttel area of northern Schleswig-Holstein state in August.
Media reports said officials believed at the time that the drones were part of a Russian espionage campaign.
However, the ARD television channel reported on Friday that the investigation into the sightings in Brunsbüttel had so far not revealed any evidence of espionage.
A spokesperson for the US Air Force said that its facilities at the Ramstein air base were unaffected.
“There was no impact on base residents, facilities or resources,” the spokesperson said.
“Together with host country authorities, we continue to monitor the airspace for the protection and safety of the community. “
Over the past few weeks, unidentified drones were also sighted in New Jersey and other parts of the northeastern United States.
On Thursday, the US federal government said in a report that there was no evidence the sightings posed a risk to national security and that some of the planes were “piloted aircraft. . . operating legally. “
In November, the US Air Force said unidentified drones had flown over three air bases in the United Kingdom.
SDI/RM (AFP, Reuters)