Ankara's decision to purchase Russian air-defence system led the tension with Washington. United States claims that they could prompt the F-35 programme. Turkish Defence Minister Hulusi Akar held a phone call with US counterpart Patrick Shanahan on Tuesday. Akar announced that he didn't receive US ultimatum over S-400 system.
In an interview with Haberturk, Hulusi Akar commented that Turkey has not received ultimatum by the US.
Turkey has proposed a working group with the United States to assess the impact of the S-400s, but stayed unresponsive, Daily Sabah reported.
According to Reuters, the US might suspend training for Turkish pilots for F-35. US State Department spokesperson Morgan Ortagus said in a statement that Turkey's acquisition of Russia's S-400 would have "very real and very negative consequences", Sputnik reported.
Russia and Turkey's S-400 deal was inked in December 2017, when the parties signed a $2.5 billion agreement for two batteries of the systems – Russia's most advanced long-range anti-aircraft missile system in use since 2007.
