On June 26, Assistant Secretary of State for European and Eurasian Affairs Dr. A. Wess Mitchell stated that the United States would sanction Turkey under Section 231 of the CAATSA should Turkey purchase the S-400 missile system from Russia. In his testimony before a Senate Foreign Relations subcommittee on U.S. foreign policy in Europe, Secretary Mitchell stressed that the United States has “been clear on multiple occasions with the highest levels of Turkish government that there will be consequences: first and foremost, what’s spelled out under CAATSA Section 231.”

Secretary Mitchell went on to say, “We’ve also been very clear that across the board an acquisition of S-400 will inevitably affect […] the prospects for Turkish military-industrial cooperation with the United States, including F-35.” Secretary Mitchell acknowledged that Turkey has been “a crucial ally and partner” with respect to counterterrorism and “in intelligence and in other areas,” but noted that the United States has communicated “that a decision on S-400 will qualitatively change the U.S.-Turkish relationship in a way that would be very difficult to repair.”