Russian espionage in Germany
During the Cold War, divided Germany had been a center of activity for the Soviet intelligence service, the KGB. It worked closely with the Ministry of State Security of the GDR and had a huge center in Berlin-Karlshorst, which controlled and coordinated KGB activities throughout Europe. After German reunification, networks of the Foreign Intelligence Service remained active in Germany.
Source: Wikipedia — Russian espionage in Germany (CC BY-SA 4.0)