"We can confirm these observations. But what it was, and to what extent, is nothing we can go into," Swedish Armed Forces press secretary Jesper Tengroth told Dagens Nyheter.
According to military reports, the units involved swapped their training blanks to live ammunition to shoot down the trespasser. Ultimately, however, they didn't open fire. Jesper Tengroth said that the Swedish Armed Forces always adapted to current threats.
The drones observed over Swenex were equipped with position lights visible in the darkness, which led to speculation that a "major superpower" was behind the encroachment in order to openly demonstrate that it had the capacity to keep a close eye on the Swedish defense.
A second incident, hitherto unknown, occurred during an Air Force exercise in September. A drone reportedly flew over the Hagshult airbase in Småland County, which led to a temporary suspension of flights.
Last week, a 33-year-old Polish citizen was arrested near Bålsta north of Stockholm during an anti-sabotage exercise by the Swedish Armed Forces. The man was reportedly taking photographs in a restricted area, near Björnen/Grizzly, one of Sweden's two larger underground facilities for the Air Defense tactical command.
All in all, 2,000 troops, 20 warships, a number of surveillance aircraft, warplanes and helicopters participated in the Swenex 2016 exercise, which was held between November 14 and 23.
"The Finnish Defence Forces possess information about isolated sightings of drone activity in military zones and exercises, but those incidents have not resulted in the same kind of disruptions as in Sweden," Mäntylä commented to Yle.
According to Mäntylä, most cases featured commercially available drones used for hobbies and amateur videos. However, he refrained from answering the direct question on whether or not foreign powers could be behind the surveillance, nevertheless ensuring that the cases presented no hazard for the Defense Forces.