Washington used all possible tricks to prevent Russian-Turkish military cooperation on this issue, but the view of the Turkish side remains the same: "They needed us (S-400) urgently, because we did not have an air defense system. We had a problem even with buying simple weapons in the US because of doubts in the congress. We had to buy from someone, "Turkish Foreign Minister Mevlut Chavushoglu said. The reason for appealing to Moscow was the refusal of Washington to sell its air defense systems to Turkey. Although the Turkish authorities do not deny that they are ready to acquire the Patriot system from the US. Although the Turkish authorities do not deny that they are ready to purchase the Patriot ABM system from the US, but this purchase will require guarantees from the US Government and Congress.
At present, Ankara is not in a very favorable position. Relations between Turkey and Washington in recent decades could not be called cloudless, however, the pressure that Washington is exerting on Ankara further exacerbates the situation. In fact, the States delivered an ultimatum to Turkey. On June 26, US Assistant Secretary of State for European and Eurasian Affairs Wess Mitchell stated that Washington would immediately impose sanctions against Ankara in the event that it acquires the S-400 from Russia. In his speech, he appealed to section 231 of CAATSA, which provides for the use of US restrictions against third countries cooperating with the defense and intelligence sectors of Russia.
Moreover, according to the White House, the purchase of the S-400 will inevitably have an impact on the prospects for military-technical cooperation between Turkey and the United States, including the F-35 fighter-bomber project. The US Senate and the British Parliament have a "good reason" for this. Thus, Senator Chris Van Hollen stated that "Turkey's purchase of both systems will allow the Russian to easily assess the capabilities of the F-35 and identify its vulnerabilities," and called this situation "unacceptable." The head of the defense committee of the British Parliament, Mark Francois, also expressed concern about the situation, as his country invests huge amounts in the F-35, so London "would not like to see" how something compromises this technology.
Finally, according to Washington, Ankara's acquisition of Russian anti-aircraft missile systems S-400 will lead to a qualitative change in bilateral relations between the US and Turkey.
This statement was the last point in the US ultimatum. The opinion of analysts on this score is ambiguous. Nevertheless, most experts are inclined to believe that Washington is trying in such a peculiar way to establish cooperation with Turkey. "We need Turkey to achieve NATO's goals, and we are now trying to reunite them with the Alliance. Make it so that their actions are consistent with our goals in NATO, "said Mike Pompeo. Ultimately, Trump's aggressive foreign policy will lead to a weakening of Erdogan's position and will force Turkey to act in the interests of Washington.