One of the two drones that strayed into eastern Finland on Sunday morning likely exploded on impact, according to former Finnish Defence Forces research chief Jyri Kosola.
Finnish authorities have not confirmed this theory.
Kosola, who is also a retired military officer and non-fiction author, said he based his hypothesis on his own personal knowledge and what people reported hearing when the unmanned device hit the ground.
"According to the information I've received, one of the drones exploded," he said.
"It made a loud bang, which a professional has identified. The bang could of course also be it hitting a tree or the forest, but my information suggests that it exploded," Kosola told Yle on Monday morning.
The Finnish Air Force has confirmed that at least one of the two drones that crashed near the city of Kouvola was Ukrainian. The device was an AN-196 drone — with a wingspan of nearly seven meters and weighs up to 300 kilograms.
Kosola suggested that both of the drones that strayed into Finnish territory were sent from Ukraine.
He characterised AN-196 as a long-range attack drone, and given it flew such a long distance, was carrying around 50kg of explosives.
"That's a large amount of TNT. If it were to hit a house, it would be badly damaged with not much left of it," he explained.
"Its range is about 1,200 kilometers, according to some sources even more," Kosola said.
The National Bureau of Investigation has opened a preliminary investigation into Sunday's incident.
Mikko Hyppönen, research director at Sensor Fusion, a Helsinki based anti-drone technology firm, also believes that the drones that breached Finnish territory were carrying explosives.
"In this case, when Ukraine has attacked targets in the Gulf of Finland with such expensive drones, I don't believe that these would be sent empty. I believe that this AN-196 has had an explosive load," Hyppönen said.
He described the AN-196 as being about half the size of a two-seater Cessna airplane.
However, Kosola said he thinks that the other drone — which fell to the ground in Orava — did not explode.
He pointed to a photo of the wreckage site of that drone, saying that an explosion would have caused more damage to the device.
The Finnish Defence Forces told Yle at 9:30am on Monday that no new drone sightings had been reported over the course Sunday night and Monday morning.
