Germany was investigating a suspected arson attack outside a defense firm in Munich on Thursday, days after two sabotage attempts on the power grid and a month after an airport drone attack that Berlin and its allies blamed on Russia.
Police arrested two people suspected of throwing incendiary devices and causing a fire at a construction site at the headquarters of Rohde & Schwarz, whose products include radar systems to detect, track and jam drones.
The suspects, a 28-year-old woman and a 38-year-old man, both Bulgarian, were arrested at a nearby petrol station, police in the state of Bavaria said.
Germany on alert after attempts on power grid
The fire caused no significant damage, and no one was injured, according to officials. Rohde & Schwarz confirmed a police and fire brigade operation near its premises. Bulgarian Interior Minister Ivan Demerdzhiev promised cooperation but declined to give details.
Germany has been the focus of European fears about the vulnerability of critical infrastructure this week.
Allies rallied round after Germany blamed a drone attack in August at Leipzig/Halle airport on Moscow as part of hybrid warfare meant to intimidate and divide countries that have supported Ukraine since Russia's full-scale invasion in 2022.
While investigations continue and the European Union weighs more sanctions, Russia strongly denies involvement and on Thursday said it would close Germany's Goethe-Institut cultural centers, reciprocating similar moves from Berlin. Poland and Britain summoned Russian diplomats, as other European allies had.
German Foreign Minister Johann Wadephul welcomed an "impressive display of solidarity" as he met Polish and French counterparts, adding: "I believe that its impact has not gone unnoticed in Moscow, either."
This week, police investigated two attempts to sabotage the electricity grid within 24 hours in the states of Brandenburg and North Rhine-Westphalia.
Interior minister warns of foreign powers using extremist group as proxies
The authorities have said they cannot rule out either foreign involvement or domestic left-wing extremists. Interior Minister Alexander Dobrindt has said foreign powers could also use extremist groups as proxies for sabotage operations.
On Sunday, a closely watched election takes place in the eastern state of Saxony-Anhalt, where the far-right, Russia-friendly Alternative for Germany (AfD) holds a commanding lead in surveys.
At the meeting with Wadephul in Weimar, Polish Foreign Minister Radoslaw Sikorski said Warsaw had summoned the Russian ambassador to express a "strong condemnation of Russian state terrorism".
In Germany's northern neighbor Denmark, the national security and intelligence service PET said Russia was recruiting Danish citizens to help plan sabotage against Danish defense firms with ties to Ukraine.
The PET has uncovered examples of Russia trying to recruit Danes on social media and gaming platforms for tasks such as taking photos of companies or infrastructure that could be used in planning sabotage, a statement said.
German investigators are also still pursuing leads in Poland and Serbia related to the Leipzig drone attack, the Spiegel magazine reported on Thursday, citing security sources.
One suspect was linked to another act of sabotage at a hardware store in Lodz, Poland, in July 2024, Spiegel reported.
Investigators are also examining links between the Leipzig attack and the discovery of a drone and explosives at the Serbian-Hungarian border, Spiegel said.
The Federal Criminal Office did not immediately respond to a Reuters request for comment. A court in the Serbian city of Subotica said proceedings were under way against two suspects.