The S-400 deal signed between Turkey and Russia has sparked an intense debate in the international arena, where harsh criticisms have been leveled against Turkey. This paper explains the reasons behind Turkey’s desire to build an elaborate air defense structure, and discuss how and why its successive attempts to reach this objective in collaboration with the allied countries have failed. It highlights the major arguments behind the severe criticisms in the West concerning Turkey’s negotiations, first with a Chinese firm, and then with a Russian firm, and how this entire process has become a serious bone of contention between Turkey and the U.S., carrying a risk of a spill over into NATO. It also discusses why and how the severe sanctions threatened to be imposed on Turkish defense industries by the Trump administration will indeed damage the security and the defensive capability
not only of Turkey, but also the U.S.