As stated by the official representative of the State Department Morgan Ortagus, these actions contradict the obligations undertaken by Ankara when joining NATO.
"We condemn in the strongest possible terms the test launches of the S-400 as incompatible with Turkey's obligations as a NATO ally and strategic partner of the United States," TASS quoted her as saying.
As noted earlier in the Turkish Ministry of Defense, Turkey expects NATO allies to discuss "alternative solutions" instead of statements criticizing the Turkish side's purchase of Russian S-400 air defense systems.
On October 23, Turkish leader Recep Tayyip Erdogan spoke about the tests of the S-400 in Turkey.