Berlin on Monday slammed Ankara's refusal to allow German lawmakers to visit a North Atlantic Treaty Organisation base near Syria and warned it could move its troops elsewhere.
The lawmakers were denied a visit to the base as it was not deemed appropriate at this time, sources in Turkey's foreign ministry told Reuters, without elaborating.
Germany uses the base as a launching pad for its part in the campaign against Isis, but Merkel announced on Monday (15 May) that troops may be moved elsewhere.
The Turkish foreign ministry barred a German delegation from meeting troops at a North Atlantic Treaty Organisation airbase.
That row was only resolved after Merkel made clear the Armenia resolution was a political statement and not legally binding, allowing German lawmakers to visit Incirlik in October.
Germany, as a member of the global coalition against ISIS in Iraq and Syria and per its agreement with Turkey, uses the airbase to station its Tornado reconnaissance jets.
Turkey approved the U.S. to fly attack and strike aircraft from the base for the fight against ISIS in early 2015.
Since the German Bundeswehr is a parliamentary army, "it is absolutely necessary for members of parliament to have access to their soldiers", Merkel said.
A spokesman for the German foreign minister said it was "completely unacceptable" for Turkey to keep members of the parliamentary defence committee from visiting their own soldiers.
Some 250 German troops are stationed at Incirlik base as part of the fight against Daesh in neighbouring Syria.
Schaefer said the Turkish side apparently wanted to convey its uneasiness over recent decisions by the German immigration authorities to grant asylum to several Turkish ex-soldiers suspected of involvement in the defeated July 15, 2016 coup attempt. Turkey has urged Berlin to reconsider.
Meanwhile, this is the latest twist in the souring of relations between the two countries.
The dispute first arose after the German parliament voted to recognized the crimes committed by Ottoman Turks against Armenians in 1915 as constituting genocide.
Erdoğan tried to host political rallies in Germany, where over a million Turks lived and were eligible to vote, but Merkel blocked the demonstrations, citing instability and security concerns.