The Mattis asked the question about the Russian "drift" a member of NATO at the briefing. He pointed to the probable incompatibility: "the Problem is how the NATO system compatible with the Russian? They will never be compatible." However, he noted that the defense Department, the United States should wait and see how Turkey will use Russian air defense system.

On the question of whether the US approves the purchase of these systems, Turkey, Mattis stressed that it was "a sovereign decision" of Ankara, RIA "Novosti".

In the week Bloomberg reported on the negotiations for the purchase by Turkey of batteries of s-400 in Russia. They started a few months ago, and Ankara is going to be spent on Russian SAM $ 2.5 billion. Two batteries will be supplied from Russia, then trade two more are planned in Turkey.

Later, the Turkish Ambassador to the Russian Federation Huseyin Dirioz reported progress in the negotiations, confirming the information the American Agency.

Bloomberg described the deal as evidence that the country is facing away from the NATO military Alliance, which linked Turkey with the West over six decades. Previously, Turkey was ready to acquire anti-aircraft missiles, but the deal never took place because of the position of NATO. Ankara was also forced to abandon plans to purchase a similar system in China under pressure from Washington.

The contradictions of Turkey with Washington were strained by US support of Kurdish fighters in Syria, which Turkey considers to be terrorists, and relations with the EU worsened after the block has opposed turning Turkey into an authoritarian state.

S-400 "Triumph" — the most modern Russian anti-aircraft missile system large and medium-range among accepted into service. It is intended for destruction of air and space attack. Each installation can provide simultaneous firing of up to 36 targets at a distance of up to 400 kilometers with guidance up to 72 missiles. S-400 can destroy cruise missiles, helicopters and planes, and ballistic targets flying at a speed of up to 4.8 kilometres per second at altitudes from a few meters to several tens of kilometers.