German authorities said on Friday that unidentified drones had been spotted flying over sensitive military and industrial sites.
Among the sites is the US air base in Ramstein, in the west of the federal 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 reported that unidentified drones had been noticed above the amenities of German arms manufacturer Rheinmetall.
Unidentified drones were also seen over the Brunsbüttel area of northern Schleswig-Holstein state in August.
According to media reports, officials believed at the time that the drones belonged to 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 hints of espionage.
A spokesperson for the US Air Force said that its facilities at the Ramstein air base were unaffected.
There were “no impacts to base residents, facilities, or assets,” 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 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 U. S. Air Force said unidentified drones had flown over three air bases in the United Kingdom.
sdi/rm (AFP, Reuters)