Police in the Bavarian city of Bayreuth recently arrested two German citizens in connection with a Russian espionage incident.

Identified as Dieter S. and Alexander J., in line with German privacy law, both are of Russian descent and are suspected of having prepared acts of sabotage in Germany on behalf of the Russian secret services. They are also accused of spying on US military bases and planning attacks on transportation routes used by the military.

The German Federal Public Prosecutor's Office has alleged that Dieter S. is "a member of the "Donetsk People's Republic foreign terrorist organization." German investigators have classified the self-proclaimed republic as a terror group, saying the "pro-Russian association took control over the Ukrainian administrative district of Donetsk from spring 2014 onward with the aim of seceding from Ukraine, and engaged in intensive clashes with the Ukrainian armed forces."

They have also said the group repeatedly used violence against civilians.

Dieter S. had been in contact with a person connected to a Russian secret service since October 2023, according to German investigators. He is also accused of having planned an act of grave violence against the German state.

The German Federal Public Prosecutor's Office said "there is strong reason to believe that Dieter S. served in a 'Donetsk People's Republic' armed unit active in eastern Ukraine between December 2014 and September 2016 and possessed a firearm."

Separatists proclaimed the "Donetsk and Luhansk People's Republics" in eastern Ukraine in the wake of the country's 2014 pro-Western opposition protests and the change of power in Kyiv. Russian President Vladimir Putin formally recognized both separatist republics in February 2022, just three days before Russia's full-scale invasion of Ukraine. In September that same year, Russia annexed Ukraine's Donetsk and Luhansk regions.

How one can end up on the terror list

"We are convinced there are constant Russian espionage efforts directed against German interests," said Thomas Haldenwang, the head of Germany's domestic intelligence service, in conversation with DW. "Germany is an important player in many policy fields with regard to supporting Ukraine."

German authorities haven't always designated the "Donetsk People's Republic" as a terrorist organization. So what explains the rethink?

There are two ways an organization can be classified as a terror organization in Germany, legal expert Matthias Hartwig of Heidelberg University told DW. One is when authorities designate it as such, another is through criminal law. Hartwig cited the example of Hamas, a radical Islamist movement, that the EU and several court rulings have deemed a terrorist organization.

While the German Federal Public Prosecutor General's Office regards the "Donetsk People's Republic" as a terrorist organization, it does not mean the German state does as well, Hartwig noted. That said, he added, it remains unclear whether the terrorist label applies to the entire separatist quasi-state structure and Russian authorities, or merely its paramilitary wing.

Hartwig assumes the German Federal Public Prosecutor General's Office regards all these separatist structures as illegal. Hartwig also said Ukraine has made it clear that these separatist structures are responsible for acts of "murder and death." It was now, therefore, up to the courts to decide whether these structures should indeed be regarded as terrorist entities, he said.

German public broadcaster ARD said the move by the German Federal Public Prosecutor General's Office to designate the separatists a terror group was a "novelty." ARD legal experts Michael Götschenberg and Holger Schmidt said "German Justice Minister Marco Buschmann had issued a prosecution authorization, a highly symbolic step that could have diplomatic consequences."

The only diplomatic consequence so far, however, has been that Germany's Foreign Ministry summoned the Russian ambassador following the espionage incident.

Legal expert Hartwig, meanwhile, has not ruled out the possibility that the espionage scandal could further exacerbate tensions between Germany and Russia.

"Germany is free to say: 'This is an annexed territory and we classify these power structures as terrorist.' Germany is not violating international law," Hartwig said.

This article was originally written in German.