OSLO, Nov. 25 (Xinhua) -- At least 10 unidentified drones have been monitoring military exercises of Norwegian troops and U.S. Marines in northern and southern Norway, public broadcaster NRK reported on Friday.
The Norwegian Armed Forces do not know who is behind the monitoring activity and the Norwegian police security service (PST) is investigating the case, according to the NRK.
The unknown drones circled above the area in the Troms county where the military exercise Rein 2 took place. Rein 2 is the army's biggest field shooting and sharpshooting exercise.
According to the report, more than 10 observations were made during the 14 days when the army was out on exercises, both in northern and southern Norway.
"For us, this represents a security threat in several ways. First of all, physically, since we ourselves fly drones and have helicopters in the air. It is very unfortunate that others fly in the same region as us," said Lieutenant Colonel Ole Johan Skogmo, spokesman of the Norwegian Army.
He added that the observations clearly broke the rules for drone operations, which limit the activity to 150 meters from personnel and material on the ground.
"We do not know who is behind the activity," Skogmo said, not excluding that it might be "curious locals who are just careless."
"However, it could also be other participants that have clear intelligence-related needs to reveal how we operate or exercise," he said.
The drones have photographed and filmed the military training activity and the armed forces take the incident very seriously. The monitoring has been related to military activities and not to any particular time of day, according the NRK.
The exercises started on Nov. 14 and were completed on Friday. There were a total of 5,000 soldiers and commandants in the exercises, including around 200 U.S. soldiers.
