A Kurdish youth group in Germany is vowing to bring destruction to Europe, following several attacks on Turkish targets. Ankara has urged Germany to do more to find those responsible for mosque attacks over the weekend.
The conflict has increasingly spilled over into Germany, home to large Kurdish and Turkish minorities.
In the latest escalation over the weekend, a Berlin mosque was set on fire by three teenagers and firebombs were thrown at a mosque in the town of Lauffen am Neckar.
The mosques are run by the Turkish-Islamic Union for Religious Affairs (DITIB), Germany's largest Islamic umbrella group, which has come under criticism for its close ties to the Turkish government.
Separately, a Turkish grocer and a Turkish immigrants' association were subject to arson attacks in other parts of Germany. There were also clashes between Kurdish and Turkish protesters in Düsseldorf and Berlin.
Roja Ciwan, a German-Kurdish website, showed videos of some of the recent attacks.
In a Monday posting, it published a call for European states that stand by or support the Turkish military operation to pay a price.
"The European states must understand that we will not stand by and watch as our people are massacred in Rojava (Syrian Kurdistan). The previous actions are not enough; here and today it is time to carry the war back to Europe."
The targets include Turkish embassies and Turkish groups with links to the government in Ankara as well as stores and cafes. The statement also threatened the offices of Merkel's conservatives, the Social Democrats, courts and police.
"Whoever supports or defends the war against our people must pay. When nobody listens we will turn the downtowns of Europe into rubble and ash. Regardless of how or what burns on this day, Europe must understand that we will not allow Afrin to fall," the youth group said.
Roja Ciwan told DW that they are journalists and have nothing to do with attacks on mosques or other institutions.
The call for violent action appears to have been sent by from the Apoist Youth Initiative, a pan-European anti-fascist group that follows imprisoned PKK leader Abdullah Ocalan, who is known to his supporters as "Apo."
The call to action comes as Kurds prepare to celebrate the annual springtime festival of Newroz on March 21, a holiday that carries heavy political undertones for Kurds around the themes of resistance and oppression.
Kurdish groups in Germany are organized under a plethora of acronyms, with most groups falling under the umbrella organization NAV-DEM. The movement gets support from Kurdish nationalists and the political left in Germany.
WorldLink: The aftermath of Erdogan's Afrin attack
Germany's domestic intelligence agency considers NAV-DEM to be closely linked to the PKK, which it calls "the biggest and most powerful foreign extremist organization in Germany."
The PKK and its myriad linked sub-organizations have been known to directly or indirectly operate youth wings.
The Berlin-based Kurdish Center for Public Relations (Civaka Azad), which is close to NAV-DEM, told DW that they have nothing to do the the call to violence.
"We are currently concentrating on preventing possible attacks and massacres on the civilian population in Afrin and calling on Germany to ensure Turkey complies with international law," a spokesperson said.
Concerns about Turkish-Kurdish clashes in Germany
Germany is home to 3 million people of Turkish origin. About a third are ethnic Kurds who came to work here in the 1960s and '70s, followed by another wave in the 1980s and '90s, fleeing conflict and persecution.
Officials have long voiced concern about conflicts between Kurdish nationalists and the Turkish state spilling over into Germany.
There were repeated clashes and attacks in Germany during the height of the conflict between Kurds and Turkey in the 1980s and '90s.
For six years, Afrin has been controlled by the YPG, a Kurdish militia that is affiliated with the PKK. The militia is the main component of the US-backed Syrian Democratic Forces fighting against the "Islamic State."