Relations with Turkey have proven one of the toughest foreign policy challenges Chancellor Angela Merkel has faced during her 16 years in power.

Turkish President Recep Tayyip Erdogan's controversial foreign policy moves, along with his verbal attacks on European states and leaders, and the severe deterioration of human rights in his country, have forced Merkel to take difficult decisions.

Her government backed the EU's soft sanctions on Turkey, restricted arms sales to its NATO partner, and even banned Turkish politicians' campaign appearances in Germany.

But despite criticism from German opposition parties, Merkel refrained from taking a harsher stance that could risk further alienating the difficult president of a strategically important country — a situation made all the more thorny due to Germany's three-million-strong Turkish community.

The longtime German chancellor maintained dialogue with Erdogan, visiting Turkey 11 times over the course of her mandates. She focused on finding ways to cooperate with him in turbulent times, and repeatedly underlined the importance of having channels of communication open in order to ease tensions in the eastern Mediterranean and seek solutions to the conflicts in Syria and Libya.

Germany's election will take place on September 26, and Merkel is set to leave power once a new government is in place. With that change on the horizon, many wonder if the next chancellor will continue Merkel's legacy — her moderate approach and diplomatic line in relations with Turkey.

Complex relationship: Deep differences, mutual dependencies

According to Eckart Cuntz, Berlin's former ambassador to Ankara, Merkel's well-balanced policy towards Turkey was the only right thing to do — despite deep differences she had with Erdogan.

"In most of the meetings of Merkel and Erdogan, the chemistry was not really the best between the two. The characters are really too different," he told DW, referring to various encounters he witnessed.

But over the years the two leaders realized that they need each other and kept a dialogue despite their sharply different views and frequently strained relations between the two countries.

"Especially with the Syrian refugee crisis, Germany recognized that one cannot solve such questions without Turkey; people realized that we have to deal with Erdogan," Cuntz said.

"I believe that the Turkish president has also understood that he cannot solve all problems without having strong partners in Europe," he added.

Merkel's refugee deal with Erdogan

The chancellor's decision in 2015 to allow hundreds of thousands of migrants fleeing civil war and humanitarian disasters to enter Germany brought her considerable blowback from the far-right and even some of her center-right party colleagues. Soon thereafter, one of her priorities became stopping irregular migration via Turkey to Europe. 

In 2016 she clinched a deal between the EU and Turkey that was successful in decreasing the number of migrants crossing the Aegean. But it made Germany and Europe "open to blackmail" by Erdogan, critics charge.

Former ambassador Cuntz says that Germany had neglected the Syrian civil war for a long time and acted too late. "If one had spoken with Turkey at the time, maybe one could have prevented major disasters in Syria. Even if one doesn't like some developments of internal politics in Turkey or some moves in external politics, we have to engage with them and also take account of Turkish concerns," he said.

According to the longtime diplomat, Germany's new government will now need to engage in a closer dialogue with Turkey, especially after recent developments in Afghanistan.

"In the case of Afghanistan, Turkey emerges as an important player once again. Not only as regards to operating the Kabul international airport but for many other questions as well. Dialogue is absolutely necessary," he stressed.

Taliban rule in Afghanistan brings new challenges

Following the Taliban's takeover of Afghanistan, diplomatic talks have already intensified between Germany and Turkey.

Magdalena Kirchner, a foreign policy expert of the Friedrich Ebert Foundation, thinks that the EU needs Turkish support to address a potential new exodus of refugees fleeing Afghanistan. "Europe is interested in expanding the 2016 refugee deal with Turkey. Because that is something that is proved as very effective," she told DW.

According to Kirchner, many rich Afghans and people from the middle class have already moved to Turkey. "Istanbul could be the hub of the Afghan diaspora," she said.

The EU aims to create better living conditions for Afghans in transit states like Turkey with the intention of preventing them from continuing their travel to Europe. But Turkey says it does not have the capacity to host more people.

Turkey has already become the largest host country for refugees and asylum seekers, and its population was tolerant of them for years. But recently the mood in Turkey — which has already accepted over 4 million refugees — has changed dramatically.

"It is also a very hot topic domestically in Turkey and has also become a weak spot for Erdogan. Because the economy is not in the state where it can absorb on top of the Syrians also low skilled labor from Afghanistan. This is something Erdogan cannot ignore. EU money cannot win [over the] Turkish public, I fear," Kirchner said. 

Human rights no longer a priority

As Turkey's EU membership talks are currently blocked as a result of tensions with Greece and Cyprus, the refugee deal remains at the center of the relationship between the bloc and Turkey. Direct dialogue between Brussels and Ankara in recent months has mainly focused on migration issues and exchanges of views on regional conflicts.

Many experts now define EU-Turkey relations as "transactional relations" in which parties do not share common goals or values, but pursue their interests and only cooperate by issue-specific transactions. 

To an extent, Germany's relations with Ankara have developed along those same lines under Merkel. But if the Green Party joins the new coalition government — which is a strong possibility — things might change.

Kristian Brakel, Istanbul office director of the Heinrich Böll Foundation, a German political foundation affiliated with the Green Party, says the EU holds little leverage over Turkey, given that EU membership talks are currently stalled.

The bloc's only current leverage is economic pressure — and there is a price to pay, Brakel told DW.

"Merkel answered the question if she was willing to pay this price with no. And the question is now: would a future German government answer this question differently?"

Deep economic ties with Turkey

For Turkey's export-driven economy, Germany is the most important trade partner, and the Turkish government is hoping to increase bilateral trade volume to $40 billion this year.

Germany remains the top trading partner for Turkey's export-driven economy. And over 7,400 German firms and Turkish firms with German partnerships are active in the country. At a time of global competition, governments find it hard to sacrifice economic interests — Merkel, for example, prioritized stability and refrained from tougher measures like sanctions even when tensions soared with Erdogan.

Yasar Aydin, a leading expert on Turkey-Germany relations, thinks Turkey's significant role in Europe's supply chains makes it extremely important for German companies.

"For Germany the security of trade lines to Asia Pacific is very important. And Turkey is a regional power in the Middle East and this region controls the trade lines to Asia Pacific," he said.

Turkey beyond Erdogan

Erdogan's Justice and Development Party (AKP) has been in power since 2002, and the next presidential election is scheduled for 2023. But many observers are expecting snap elections next year, and the latest polls show that support for Erdogan is eroding. Whether he will run for another term as president is unclear.

"In Germany and Europe everyone is waiting for the post-Erdogan era. I see it [as] possible, although we know that he is a tough fighter and he will not leave without a fight. But the Turkish opposition is stronger and they have a real chance of winning the election this time," Yasar Aydin said. "German politicians also know this, and the new German government will likely wait for this moment before taking major steps to improve the relations," he added.

DW's Luisa von Richthofen and Julia Hahn contributed to this report.

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