"The sides have discussed the situation around [the deliveries of Russian missile defense systems] S-400 and [US fighter jets] F-35, as well as the situation in Syria’s Manbij and Idlib and the creation of a safety zone in Syria," the source noted.

ANKARA, July 20. /TASS/. Turkish Foreign Minister Mevlut Cavusoglu and US Secretary of State Mike Pompeo have held talks over the phone regarding the situation around Russia’s S-400 missile defense systems and US F-35 fighter jets, a source at the Turkish Foreign Ministry informed reporters on Saturday.

This is the first contact between the US and Turkey after the start of the deliveries of Russian S-400 missile defense to Turkey and Washington’s statement on the exclusion of Turkey from the F-35 fighter jet program.

The S-400 contract

The news about the Russian-Turkish talks on the purchase of S-400 systems first came in November 2016. The Russian side confirmed that the contract had been signed on September 12, 2017. Concurrently, Turkish President Recep Tayyip Erdogan announced that Ankara had made an advance payment. Turkey is going to become the first NATO member state to purchase an air defense weapon of this class from Russia.

US officials warn that Turkey’s contract to purchase S-400 missile systems from Russia will severely damage bilateral relations and lead to unilateral US sanctions against Ankara.

Earlier, the Pentagon informed that in order to remain in the F-35 fighter jet program, Turkey needs to drop the purchase of Russia’s S-400 missile defense systems.

The White House said in a statement on Wednesday that "Turkey’s decision to purchase Russian S-400 air defense systems renders its continued involvement with the F-35 impossible." However, Washington pointed out that it will "continue to cooperate with Turkey extensively, mindful of constraints due to the presence of the S-400 system in Turkey." The Turkish Foreign Ministry called on the United States on Thursday to reconsider this decision, which "may deal irreparable harm to bilateral relations.".