"The United States may soon stop preparations for the delivery of the F-35 fighter jets to Turkey, while that will be a strong indication by Washington so far as Ankara cannot own the advanced aircraft and the Russian missile defense system S-400 at the same time," officials said to Reuters.
Since years, the United States has been approaching a milestone in a long-standing standoff with Turkey, its NATO partner after it has failed so far to convince the Turkish President Recep Tayyip Erdogan that buying the Russian air defense system would undermine the security of F-35s.
Although no decision has been made so far, US officials have confirmed that Washington is considering halting steps being taken to supply Turkey for F-35s manufactured by Lockheed Martin Company.
"There are ongoing decisions on what things are being delivered in anticipation of owning aircrafts eventually," said Katie Wilberger.
"So there are many things that can be stopped in order to send signals to them (that we are serious)," she said and did not elaborate the procedures.
Another US official said that of such measures, the United States must look for alternative sites for engine depots in Turkey, and he did not mention any further details. The official added that the possible alternatives would likely be in Western Europe. Turkey has a warehouse to repair F-35 engines in the city of Asky Shahr west of the country.