Relations have been quite tense between Turkey and Germany for some time now. Last year, the German parliament had recognized the incidents in the late Ottoman Empire in 1915 as "genocide." Germany is, of course, not the only country in the world to have qualified in that manner what happened to the Ottoman Armenians. After every decision of recognition, Turkey issues statements of denunciation and repeats the same diplomatic reaction. To be honest, despite its reaction, Turkey does not allow the recognitions to poison bilateral relations for too long, and acts as if this recognition did not happen. Therefore, one cannot argue that the German parliament's decision is the recent main problem between Ankara and Berlin, and one has to look for other reasons.
Turkey believes that Germany has a systematic policy of protecting the enemies of Turkey. For example, most Turks believe that Germany is, and has always been, a safe haven for PKK terrorists. In the wake of the July 15, 2016 coup attempt, things have gotten even worse, as Turkish people's perception about Germany has deteriorated: According to them, this country is not only protecting Turkey's enemies, but it has an openly hostile attitude toward Turkey.
You may recall that German authorities have granted asylum to Turkish military personal who have taken part in the coup attempt, a move that has exacerbated bad feelings about Germany. The Turkish decision makers genuinely believe that Germany is now openly against the current Turkish government.
In this negative context, Turkey has decided not to allow German parliamentarians to visit German troops deployed in Turkey's İncirlik Air Base. It is hard to understand why those parliamentarians want to meet in person with the German soldiers. What is going to change if they visit them or not? Yet the issue has become some sort of an arm wrestling competition. The eventual visit is, of course, just a pretext.
Germany is not only insisting, but also blackmailing Turkey about this visit. They have recently announced that they will wait for another 15 days, and then, if Ankara maintains its position, they will deploy their troops elsewhere, for example in Jordan.
Should Turkey worry about the retrieval of German troops? I think not. Those soldiers may easily be replaced by other NATO troops. However, such a move will deteriorate Turkish-German relations further.
Just like the genocide issue, İncirlik cannot be the issue that explains why relations are so bad between the two countries nowadays. One cannot help to ask whether or not Turkey has become a serious obstacle for a number of objectives of the German government.
It is obvious that Turkey, alone, cannot impose its own will to major powers, but it can perfectly disrupt the plans elaborated by those powers. Maybe Germany is upset with the recent rapprochement between Turkey and Russia, who knows? We know that Russia is blocking Germany's relations with Ukraine and Iran at a time when Berlin was hoping to become an influent player in Eastern Europe, Middle East and the Caucasus. Turkey has played a role in this, by normalizing its relations with Russia in a relatively quick manner.
The second issue is probably related to Syria. We know that Germany has been "investing" in the Kurdish terrorists in Turkey and Syria for quite a long time. Yet, U.S. and Russian military presence in Syria makes it difficult for Germany to have direct influence over Syrian Kurdish extremist groups. Thus, Berlin is probably thinking that they have only the outlawed PKK at hand to be able to matter in Middle Eastern balances.
We must not forget, of course, that the frictions between Turkey and Germany are not independent from the big picture, i.e. the evolution of the global balance of power. Let's hope the great powers come quickly to an agreement about their long term strategies and find compromises with one and other.