The development comes after Washington reiterated its warning last week that if Turkey purchases the S-400 systems, Washington will have to reassess Ankara’s participation in the Lockheed Martin F-35 fighter jet programme.
Reuters has quoted unnamed US officials as saying that Turkey’s push to purchase Russian S-400 missile systems along with US F-35 fighter jets poses a national security problem to NATO.
Earlier, Turkish President Recep Tayyip Erdogan, for his part, reaffirmed his country’s commitment to the S-400 deal with Russia and added that the acquisition of advanced S-500 systems is also on the table.