German security services prevented a suspected assassination attempt on Stefan Thumann, head of defense company Donaustahl, according to a document from the Federal Office for the Protection of the Constitution. The case is described as an alleged planned assassination and is regularly discussed at the Federal Chancellery's weekly intelligence briefings.
German intelligence received a signal in December 2025 from a foreign intelligence service that Thumann was at heightened risk. Shortly after, Sergei N. appeared in Strasskirchen, Lower Bavaria. He approached Thumann's home, filmed the entrance with his phone, and photographed the nameplate. Bavarian police detained Sergei N. and seized his phones, but could not decrypt the data during the detention period and released him.
Later it emerged that he had been in contact with a Russian intelligence service and had also tried to surveil Thumann's father to determine his son's whereabouts. By that time, Sergei N. had already left with his family for Spain, and surveillance of the entrepreneur was continued by Alla S., a Romanian citizen living in North Rhine-Westphalia. In March 2026, both were detained — he in Spain, she in Germany.
Neither was a career intelligence officer; investigators consider them "disposable agents" recruited online from vulnerable or semi-criminal circles. The assassination itself, according to the investigation, was to be carried out by other operatives. A judge at Germany's Federal Court of Justice did not include the murder plot version in the arrest warrant, which only mentions suspicion of espionage activity.
Thumann founded Donaustahl in 2019, and since 2023 the company has produced drones. He has publicly and harshly criticized Russia, writing on his LinkedIn page: "Russia does not want peace. It wants the destruction of the West." The entrepreneur is now under heightened security and told followers he cannot attend exhibitions "for certain reasons." He also published a letter from the prosecutor's office regarding his case and wrote: "Dear minions of Moscow... you will not break me."
According to Die Zeit, another defense company is in the sights of Russian intelligence, and investigators do not rule out that its head's life is also in danger. The materials are classified. On June 11, Serbian border guards stopped a truck at the border with Hungary with hidden compartments carrying explosives, and in the drivers' phones found contacts with a Russian intelligence service; the vehicle's destination was Bavaria, where besides Donaustahl, Quantum Systems and Helsing operate. A court in Serbian Subotica confirmed to Die Zeit that suspects Danilo B. and Slobodan Dj. are in pretrial detention.
As early as 2024, data emerged that Russian agents were following Rheinmetall CEO Armin Papperger. Berlin assumes such tasks could not have been planned without Kremlin approval.