A long motorcade of cars made its way through Berlin in rush hour traffic. People were honking, chanting and holding banners with the slogan #FreeDeniz. Usually such motorcades are reserved for big wins by the German national team. This time, though, the cars were there to highlight the case of Deniz Yucel, a German journalist who is now being detained in Turkey.

After driving several kilometers across the city center of Berlin, the motorcade arrived in front of the Turkish embassy. It was one of several demonstrations nationwide on Tuesday evening to call for the journalist's release. Members of the opposition parties in parliament, the Greens and Left Party, had gathered there, together with activists, Berlin residents and journalists, many of them from Die Welt, the newspaper Deniz Yucel works for. Similar protests, to show solidarity, were planned for eleven other cities nationwide, as well as Vienna and Zurich.

One of the protesters in Berlin was Cem Ozdemir, one of eleven members of parliament of Turkish descent and an avid critic of Turkey's president Erdogan. He told DW: "It's important to make clear, that the times of cuddling up to Mr. Erdogan are finally over. He only takes that as a sign to stay his course. We have to stop throwing cotton balls at him and instead be very clear." Ozdemir's criticism was directed both at German Chancellor Angela Merkel and German Foreign Minister Sigmar Gabriel.

Ambassador summoned

In the meantime, Gabriel called in the Turkish ambassador on Tuesday to make him aware of the fact that "there are huge differences in the freedom of the press and freedom of opinion between the two countries."

He said the jailing had placed a massive strain on bilateral relations. Relations between the two countries "stand right before one of the greatest load tests of the present time," he said.

Cem Özdemir and Özcan Multu, both of Turkish descent and members of the Green party in parliament, protested in front of the Turkish embassy in Berlin

First German journalist to be jailed since 2002

Yucel's case is unparalleled: He is the first German journalist who has been jailed in Turkey since President Erdogan's party, AKP, came to power in 2002. Yucel has both German and Turkish citizenship. Turkish authorities had initially detained the German correspondent of Die Welt newspaper on February 14 on charges of propaganda in support of a terrorist organization and inciting violence. A formal indictment is still pending.

Yucel's arrest came after he reported on emails that a leftist hacking collective had obtained from the private email account of Berat Albayrak, Turkey's energy minister and President Erdogan's son-in-law. A number of Turkish media outlets had refrained from reporting on the explosive emails. During the investigation, Yucel was not only asked about his articles on the emails, but also about an interview he conducted with Cemil Bayik, a commander of the Kurdistan Workers' Party (PKK). This group is outlawed in Turkey on the grounds that it is a terrorist organization. According to Die Welt, Yucel was also questioned about several reports that are critical of the Turkish government's treatment of ethnic Kurds.

Deniz Yücel's case is unparalleled

Tens of thousands arrested in Turkey since failed coup

The arrest is part of a widespread crackdown by the Erdogan administration that has targeted the media, civil service and academics, as well as military and police sectors, following last year's failed July 15 coup. Since July 2016, more than 100,000 people have been sacked or suspended, tens of thousands have been arrested. So far, foreign reporters have mostly been spared, and they have enjoyed more liberties than local journalists. But Turkish authorities reportedly chose to treat dual-citizen Yucel as Turkish, rather than a German.

German politicians agree: Yucel must be freed

In Germany, a country that used to be one of Turkey's close allies and cooperated closely with Turkey as part of NATO, the case of Deniz Yucel has been criticized harshly by both the German government and the opposition parties.

In fact, Yucel's treatment is the one topic that all parties in the German parliament are currently able to agree on - from the Left Party to Merkel's Christian Democrats.

Relations between Turkey and Germany have been tainted by a number of incidents in 2016, including the vote in German parliament to recognize the Armenian genocide. Death threats, especially against the 11 members of the Bundestag with Turkish roots, came pouring in after the vote, while German politicians weren't allowed to visit German troops at the Turkish military base Incirlik. Yet after the failed coup attempt in Ankara in July, Merkel and her government were slow to condemn the events

Relations between Turkey and Germany have been tainted by a number of incidences

Germany needs Turkey

But Germany, and especially Angela Merkel, who has come under pressure because of her refugee policies, desperately need Turkey to uphold a so-called ‘refugee deal' that controls the flow of migrants into Europe.

Since the deal was cut between the EU and Turkey in March 2016, the number of migrants crossing the Sea from Turkey to Greece has dropped from an average 1,740 to 89 per day, according to the European Commission.

Merkel has often refrained from harsh criticism of Turkey's human rights practices in the past and has been strongly criticized for her lack of "clear words" by the opposition in parliament. The case of Deniz Yucel puts the German chancellor in a tough spotonce again, just six months ahead of a federal election in Germany that Merkel said will be the toughest she has had to face in her career.

Watch video 00:53 Berlin protester talks to DW

Yucel's arrest "bitter and disappointing"

Angela Merkel's assessment of Yucel's detainment, however, was untypically candid. She criticized Yucel's arrest as "bitter and disappointing" as well as "disproportionate."

"The German government expects that the Turkish justice system keeps in mind the great importance that press freedom has in any democratic society in its treatment of the Yucel case," she said. "We will continue to insist on a fair and legal treatment of Deniz Yucel and hope that he will soon regain his freedom."

Germany's top diplomat Sigmar Gabriel was even more candid in his response to the case. The new foreign minister expressed his dismay, saying Ankara was exacerbating what were already "dramatic times for German-Turkish relations."

Yucel is just the tip of the iceberg

At the protest in Berlin, Yucel's colleagues, and other journalists, were hoping that the Turkish government would listen to their demands to release Deniz Yucel.

But at a time when German-Turkish relations are at their lowest point in decades, Yucel is only the tip of the iceberg. But one that will most certainly inflict further serious damage to the two countries' relationship.