Sweden's domestic security agency said on Monday it has taken over the preliminary investigation into drones that last week were seen hovering over or near the country's three nuclear power plants.
At first, police said there had been drones over two nuclear plants - Forsmark, north of Stockholm, and Oscarshamn in the southeast. The intelligence service, known by its Swedish acronym SAPO, said a drone also was reported over a third nuclear power facility, Ringhals, which is the largest of them and sits on the country's western coast.
Police have no suspects.
With regard to the cases of drone overflights at three nuclear power plants, the assessment is made that they are of such a nature that preliminary investigations have been taken over from the police authority in order to be able to investigate the incidents in more detail, SAPO said in a statement.
Late Friday, police were alerted about the drones but lost track of the unmanned aircraft. Swedish media said the drones were large enough to withstand the wind that was blowing over the area.
Hans Liwang, an associate professor with the Swedish National Defense College, told Swedish broadcaster SVT that Sweden is not sufficiently prepared for this type of event.
We have not really adapted our way of looking at this type of event to today's reality, he said. We still think of the world as either at peace or at war.
In 2019, the Ringhals 2 reactor in southwestern Sweden was permanently shut down with operators citing a lack of profitability and rising maintenance costs.
On top of that, there are two decommissioned nuclear power facilities in Sweden - Barseback, which sits on the narrow waterway between Sweden and Denmark, and Agesta, south of the Swedish capital of Stockholm.