On the night of September 2 to 3, incendiary devices were thrown from a car onto a construction site next to the headquarters of two German defense companies in Munich - Helsing and Rohde & Schwarz. Two of the devices ignited, the third didn't go off. Major damage was avoided and no one was hurt. Police soon arrested a 28-year-old woman and a 38-year-old man, both Bulgarian nationals.

German investigators are now checking whether the two were just the last link in a wider network tied to Russia's military intelligence service, the GRU, German media report. The targets speak for themselves. Helsing makes military drones and supplies them to Ukraine, while Rohde & Schwarz develops military electronics, communication systems, radars and equipment for detecting, tracking and jamming drones. That's exactly why the investigation is checking whether the attack is directly linked to support for Kyiv.

It's worth being precise: so far there is no publicly released conclusive evidence that the GRU ordered the attack. That's the investigation's working theory, and Moscow rejects accusations that it is behind sabotage in Europe. The problem is that Munich isn't an isolated case.

At the same time, according to the same reports, sabotage was being prepared against the factory of Ukrainian drone maker Skyeton in the Slovak town of Haniska. Slovak prosecutors said at the end of August that there had been an attempt to set the factory on fire, but the attack was foiled. Two Latvian nationals and one Ukrainian national were arrested. German security services suspect a dedicated GRU unit responsible for special operations abroad is behind some of the sabotage across Europe.

Berlin had earlier accused Russia of attempted sabotage at Leipzig/Halle airport, where in August a drone carrying explosives was found near a Ukrainian An-124 transport plane. On September 1 the German authorities officially linked that case to Russia, and Moscow denied that too. According to reports, German services are also examining links between Leipzig and other sabotage suspects across Europe, including leads that point to Poland and Serbia.

In Munich - Bulgarian nationals. In Slovakia - Latvians and a Ukrainian. In the Leipzig investigation - leads to Serbia. Hybrid war isn't fought with tanks, but with people throwing incendiary devices from cars at night, while no one can say for sure who gave them the order. German investigators are now trying to establish whether Munich, Slovakia and the earlier cases are parts of the same network or separate operations. How many threads of that network run through the Balkans?