Relations between the United States and Turkey have become tangled into a knot. Attempts to reach a compromise on the issue of Syrian Kurds have repeatedly stumbled, whereas Ankara’s purchase of the Russian S-400 anti-aircraft missile system is believed to threaten “NATO solidarity” with erosion. Turkey has reportedly about two weeks to decide whether to buy American Patriot missiles or face harsh penalties for the deal with Russia. The Turkish Foreign Ministry slammed this ultimatum, and so did Russia.

"We are going on the many statements made by representatives of Turkey's leadership headed by President [Recep Tayyip] Erdogan that the S-400 deal is already complete and will be implemented,” Kremlin spokesperson Dmitry Peskov said on Wednesday.

"We regard this [US position] extremely negatively. We consider such ultimatums to be unacceptable," Peskov added.

Turkey is obviously trying to maintain the balance of interests. Ankara demonstrates steadfastness, declaring that expanding the cooperation with Russia is possible, and shows that it is getting prepared for potential restrictions yet still hoping for a reasonable compromise.