The German government announced on 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 cites a report from the German security government stating that several drone sightings were recorded over the Ramstein base 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 broadcaster reported on Friday that investigations into the sightings in Brunsbüttel have as of yet unearthed no indications of espionage.
A spokesman for the US Air Force said its facilities at Ramstein Air Base were affected.
There were “no impacts to base residents, facilities, or assets,” the spokesperson said.
“Together with the authorities of the host country, 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 authorities said in a report that there was no evidence that the sightings posed a national security threat and that some of the devices were “manned aircraft … operating lawfully.”
In November, the US Air Force said that unidentified drones were spotted over three air bases in the United Kingdom.
sdi/rm (AFP, Reuters)