Berlin-

Two German and Russian men have been arrested in Germany on suspicion of espionage, with one accused of agreeing to attacks on potential targets including U.S. military installations in a bid to disrupt aid to Ukraine, prosecutors said Thursday.

Federal prosecutors said the two men, identified only as Dieter S. and Alexander J., were arrested in the Bavarian city of Bayreuth on Wednesday due to German privacy rules.

Prosecutors said that since October, Dieter S. had been discussing possible acts of sabotage in Germany with a person with ties to Russian intelligence, primarily aimed at undermining German military support for Ukraine.

The suspects declared themselves willing to carry out bombing and arson attacks on infrastructure used by German military and industrial sites, prosecutors said in a statement. They added that he gathered information about potential targets, including U.S. military installations.

Alexander J. allegedly helped him do this starting in March at the latest, while Dieter S. scouted locations, took photos and videos of military objects and passed the information to his intelligence contacts.

On Wednesday, a judge ordered Dieter S. detained pending possible prosecution, and on Thursday, Alexander J. was ordered detained.

Dieter S. also faces separate charges of belonging to pro-Russian separatist forces in the Donetsk region of eastern Ukraine between December 2014 and September 2016.

Since Russia began its full-scale invasion of Ukraine more than two years ago, Germany has become Ukraine’s second-largest arms supplier after the United States. The United States maintains a large military presence in Germany, including Bavaria.

Prosecutors did not disclose any specific locations where the suspects were seen. German news agency dpa and Der Spiegel magazine reported that the locations allegedly spied on included the U.S. military base in Grafenwoehl, without citing sources.

Germany’s top security official, Interior Minister Nancy Feser, said the Russian ambassador had been summoned to the Foreign Ministry in Berlin.

She vowed that Germany would continue to thwart any such threats from Russia. “We will continue to give strong support to Ukraine and will not allow ourselves to be intimidated,” she said.

Feather would not comment on the details of the investigation. She said that since Russia sent troops to Ukraine in 2022, Germany has strengthened its security measures and will continue to evaluate them.

Kremlin spokesman Dmitry Peskov said he could not comment on reports of the arrests, adding that he had “no information on the matter.”

European officials have recently warned that Russia-linked interference networks are seeking to undermine European support for Ukraine’s war with Russia.