Finland has closed the investigation into four Ukrainian drones. According to authorities, navigation jamming and weather contributed to their diversion

At the request of the Central Criminal Police and the Border Guard, the Finnish prosecutor has closed the investigation into four drones that fell on Finnish territory in spring. In a joint announcement, both authorities state that all four came from Ukraine, were of the same type, manufactured for military use, and were part of Ukrainian countermeasures triggered by Russia's war of aggression. According to the authorities' assessment, each of them had explosives attached.

According to the announcement, the diversion from the original route was influenced by strong jamming of satellite navigation in the eastern part of the Gulf of Finland and by the weather conditions at the time. The Finnish authorities do not name the specific transmitter or the country from which the jamming originated. An explanation of where the signal came from was offered by a British journalistic reconstruction from May, which is a different type of source than an official finding.

Four drones, four locations, no charges

The first two devices fell in southeastern Finland on March 29, one north of Kouvola in the Kymenlaakso region and the other in Luumäki in South Karelia. The Border Guard found the third on March 31 on the ice of Lake Pyhäjärvi in the municipality of Parikkala, in the border zone. The fourth was added on April 11 in Iitti in the Päijät-Häme region. In the case of the device from Luumäki, police believe it exploded while still in the air; the remaining three were destroyed by bomb disposal experts in controlled explosions. No one was injured and no property damage occurred. Lentoposti ↗ Yle ↗

The Border Guard handled the cases as suspected territorial violations, while the criminal police treated them as suspected general endangerment through negligence, including its more serious form. According to the announcement, how the devices reached Finnish territory was clarified through technical examination, observations, and international information exchange, with the authorities cooperating with, among others, the Ukrainian authorities. In the end, no charges were filed. "The preliminary investigations have not revealed any evidence that would have justified continuing the pursuit of criminal liability," the joint statement notes. Yle ↗ Lentoposti ↗

The authorities add a sentence worth reading twice: closing the case does not mean that the devices did not unlawfully enter Finnish airspace. According to the announcement, their unauthorized entry met the criteria of a territorial violation; it was simply that no grounds were found for further pursuing criminal liability. According to the authorities, Finland was not the intended target in any of the cases. Lentoposti ↗

Ukraine apologized to Finland as early as the end of March, after the first two devices were found in southeastern Finland. According to a representative of the Ukrainian Ministry of Foreign Affairs, Finland was under no circumstances the target, and the devices likely reached its territory due to Russian signal jamming. Yle ↗

How exactly the cause is worded determines what can be read out of the article. The announcement speaks of strong jamming of satellite navigation in the eastern part of the Gulf of Finland and of the weather, with the wind blowing almost directly from the south at the time of the incidents. According to the authorities' assessment, these factors affected the devices' navigation and their diversion from the original route. The report does not state who was causing the jamming. Lentoposti ↗

How to convince a drone that it is somewhere else

How navigation jamming can divert an armed device was already described in May by the British daily The Telegraph, and its explanation was then picked up by Finland's public broadcaster Yle. According to it, a transmitter has been operating in Kaliningrad for several years, but Russia is reportedly now able to use it in a way that first prevents a drone from determining its own position and then sends a signal stronger than any other the device picks up. This is a general mechanism, not a finding specific to these four cases. Yle ↗

According to this explanation, the spoofed signal convinces the device that it is deep inside Russian territory — that is, much further than it actually is. The drone therefore corrects its own course toward the west to return to where it thinks it should be, and instead of the Russian target, it flies into the airspace of NATO countries. This is the difference between ordinary signal jamming and spoofing false data, in which the device still "sees" a position, just the wrong one. Yle ↗

According to the newspaper, the same transmitter is also able to disrupt the onboard computer's time data. Ramsey Faragher, director of the British Royal Institute of Navigation, explains that the drone may then believe it is, for example, a decade later, which can lead to an in-flight restart or a complete shutdown followed by a crash. According to the Telegraph, Ukraine is aware of this problem and is trying to address it. Chatham House analyst Keir Giles told the newspaper that Russia will not stop doing this, "because there will be no costs or consequences imposed on Moscow, and the return on the effort they are putting in is enormous". Yle ↗

Why read this from Slovakia

Slovakia is a member of the same alliance, and airspace restrictions prompted by drone threats have recurred on its eastern flank in recent weeks. We wrote about the night of September 1, when the Finnish military preemptively closed part of the sea and airspace off Kotka, people in eight Estonian counties received an alert to seek shelter, and NATO fighter jets took off from the Ämari base.

Also read: Zelensky declared Russian airspace dangerous for civilian flights

The Finnish case points to something that is easily lost in reports like this. An armed device can end up on the territory of a country that was not its intended target, and the investigation can still close without anyone bearing criminal responsibility. Moreover, these are not just four isolated cases: on May 3, the Border Guard also dealt with two more drones that flew through Finnish airspace along the border near Virolahti and then flew back across the border into Russia. Lentoposti ↗

Meanwhile, Finland and Ukraine have moved from incidents to cooperation. On May 3, on the sidelines of the European Political Community summit in Yerevan, Zelensky urged Prime Minister Petteri Orpo to have Finland join the Ukrainian Drone Deal agreement, and Orpo promised that the proposal would be considered. Then, in late August, during President Alexander Stubb's visit to Kyiv, Finnish and Ukrainian companies signed three documents on drone development and production, on maritime unmanned systems, and on the production of ground robotic systems. According to Stubb, the intergovernmental Drone Deal agreement had not yet been concluded at the time of the August visit. Yle ↗ Helsinki Times ↗

Limits of this account

We know what conclusion the investigators reached, not exactly how they reached it. The authorities published a summary, not the case file, so we have no way to independently verify their conclusion about navigation jamming and weather.

Two things need to be separated. That navigation jamming in the Gulf of Finland influenced the diversion of the drones is what the Finnish authorities say. That a specific transmitter in Kaliningrad is behind such jamming was written by a British newspaper based on experts it consulted, more than three months before the Finnish findings were published. Linking the two claims is journalistic, not official.

How easily these two layers blend together is shown by the way the report itself was picked up. The English version of Yle inserted into the official findings a sentence saying the devices had probably been "hijacked" in flight and redirected westward, and referenced the May article about the Telegraph. The Ukrainian outlet European Pravda then went further and wrote outright that the drones "were intercepted by GPS-jamming systems in Kaliningrad and redirected towards Finland", presenting it as part of the Finnish authorities' findings, without any qualification. Kaliningrad does not appear in the announcement itself. Yle ↗ European Pravda ↗

Finally, the cited sources do not include any Russian response to the claims about satellite navigation jamming originating from its territory.

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