Moscow's intervention in an alleged rape case involving a German-Russian girl has heightened suspicions in Berlin that it is trying to stir up trouble, with a view to weakening Chancellor Angela Merkel.
The case of the 13-year-old, named only as Lisa F., became the focus of political intrigue after she told police that she had been kidnapped in east Berlin last month by refugees who raped her while she was held for 30 hours.
Senior German officials believe Russia is trying to erode public trust in Merkel using immigration, an issue which has badly damaged her opinion poll ratings and divided European Union governments over who should accommodate asylum seekers pouring in over the past year.
By undermining Merkel, who has taken a tough line on the Ukraine crisis, Moscow hopes to destabilise Europe and create a vacuum into which it can project its own power, they say.
"There is a Russian attempt to strengthen disunity in the EU and to work with anti-European, right-wing populist parties," said one senior official, speaking on condition of anonymity.
The Kremlin could not immediately be reached for comment.
"The refugee crisis and the Lisa case have allowed [Moscow] to exploit more strongly groups like Russian Germans, and to play with Germans' angst and insecurities," said Stefan Meister of the German Council on Foreign Relations, a think tank.
The case has provoked outrage among Berlin's Russian community and Russian media have reported extensively on it.
Russians protested in Bavaria at the weekend, after about 700 people had demonstrated in front of Merkel's office, some holding banners reading "Our children are in danger" and "Today my child, tomorrow yours."
"The aim is to weaken the EU," the senior German official said. "Moscow is targeting the strongest, most stable country - Germany. Of course it is in the interest of this Russian government to weaken Merkel as the leader of this country."
Another senior German official added: "The EU cannot allow third parties to split the union."
Merkel's relationship with Putin is cold, illusion-free and grounded in a hard-nosed realism born of her own experience growing up in a Soviet garrison town in East Germany. She recognises that the former Soviet agent respects firmness.
Thus, she was firm in her role as chief mediator in the Ukraine crisis, and has since been implacable in her refusal to ease sanctions against Russia that are intended to punish Moscow for annexing Crimea and supporting separatists in eastern Ukraine.
"Should Merkel fall over the refugee crisis, there would be no hold-up in the EU any more in doing away with the sanctions," said Meister.
Merkel's allies are closing ranks around her over Ukraine and Berlin's technical help for Western airstrikes on Syria, although its jets are not doing any of the bombing.
"Germany must send clear signals to Moscow and stay its course on the Ukraine/Russia conflict and with Syria," said Roderich Kiesewetter, a foreign policy spokesman for Merkel's conservatives in parliament. "Only in this way can it be made clear to Russia that constructive, diplomatic cooperation serves both sides."