Diplomatic relations between NATO members Germany and Turkey hit rock bottom on Monday when Germany's foreign minister Sigmar Gabriel said his country has no choice but to begin the process of pulling its forces out of Turkey's Incirlik air force base as the Turkish government will not allow all German lawmakers to visit troops there.

"Turkey has made clear that, for domestic political reasons, it cannot approve visits of all lawmakers," Gabriel told a news conference after meeting Turkish Foreign Minister Mevlut Cavusoglu in Ankara.

The scandal erupted last Thursday, when Turkey's foreign minister said it is not possible to allow German lawmakers to visit troops stationed at Turkey's Incirlik air base now, although he said Ankara may reconsider if it sees "positive steps" from Berlin. It was not immediately clear just what Turkey's "demands" or expectations, monetary or otherwise, were from Merkel for it to change its view. Ties between the NATO allies deteriorated sharply in the run-up to Turkey's April 16 referendum that handed President Tayyip Erdogan stronger presidential powers.

"We see that Germany supports everything that is against Turkey," Mevlut Cavusoglu told a news conference in Ankara last week. "Under these circumstances it is not possible for us to open Incirlik to German lawmakers right now ... If they take positive steps in the future we can reconsider."

The recent deterioration in relations between Germany and Turkey developed when Germany, citing security concerns, banned some Turkish politicians from addressing rallies of expatriate Turks ahead of the referendum, infuriating Erdogan. Ankara responded by accusing Berlin of "Nazi-like" tactics. Germany also expressed concern about the widespread security crackdown that followed last year's failed coup in Turkey as a result of which more than 100,000 people have been sacked or suspended from their jobs and more than 40,000 people jailed.

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Fast forward to Monday morning, when cracks in NATO's unity, if not its brand new steel-and-glass headquarters emerged, when speaking in a press conference in Ankara with German Foreign Minister Sigmar Gabriel, Turkish Foreign Minister Mevlut Cavusoglu said German lawmakers can visit a military base in Konya, but not the main NATO base, Incirlik, in southern Turkey. Cavusoglu said Turkey-Germany ties are in a distressed period, blaming PKK activity in Germany and saying the presence of followers of Gulen movement are harming relations.

Cavusoglu also said secret services have started to "use journalists" in Turkey and added that journalist Deniz Yucel was arrested on terrorism charges, not due to his reporting.

In comments via live translation to Turkish, Gabriel said German military can’t constitutionally remain at a base abroad if lawmakers cannot visit them and said that since its operations are approved by parliament, German lawmakers must be able to visit the Bundeswehr, Gabriel added.

"Turkey must understand that in this situation, we must transfer German soldiers out of Incirlik," he said. "In this situation, the Bundestag (parliament) will ask the government to find another location for the German soldiers in Incirlik."

In the last week of May, Angela Merkel gave her strongest signal yet that she’ll pull German troops out of Turkey unless President Recep Tayyip Erdogan lets lawmakers in Berlin visit them, further cracking a show of unity at a NATO summit. At the North Atlantic Treaty Organization meeting where U.S. President Donald Trump hectored European allies to pay more for defense, Merkel confronted Erdogan about access to the soldiers at the NATO base in Incirlik where Germany stations reconnaissance jets that fly missions over Iraq and Syria.

“I’ll make very clear in my discussion with the Turkish president that it’s essential for us, because we have a parliamentary army, that our soldiers can be visited by members of the German parliament,” Merkel told reporters before the bilateral meeting. “Otherwise, we’ll have to leave Incirlik."

Earlier this month, Merkel called Turkey’s stance on visits to Incirlik “deplorable” and said Germany may move the warplanes based there to a location outside Turkey, possibly Jordan.

It appears that in addition to its Trump-related headaches, NATO may be splintering on its own as Turkey increasingly defies the most powerful nation in Europe.

It was not immediately clear if and when Germany would follow through on its threat and begin the withdrawal of troops from Incirlik; it was also not clear if other NATO members would join Germany and pull their forces from the strategic airbase in sympathy.