The delivery of Russian S-400 to Turkey may have ‘devastating’ consequences for the program of F-35s, Kathryn Wheelbarger, acting assistant secretary of defense for international security affairs told an audience at the Atlantic Council in Washington.

"Completion of this transaction would be devastating, not only to the F-35 program, on which the West has placed its modernized integrated air capability, but it would potentially rupture Turkish interoperability with NATO, a key aspect of the defense of the alliance," France24 reported quoting Wheelbarger. 

"Let's be clear. The S-400 is a Russian system designed to shoot down an aircraft like the F-35, and it is inconceivable to imagine Russia not taking advantage of that collection opportunity,” she said. "Once you introduce Russian systems, it really undermines our ability to continue helping them to defend themselves.”

On May 22, CNBC, citing sources, reported the US s delivered a two-week ultimatum to Turkey: Ankara is either refusing to acquire Russian S-400s, or withdraw from the program to create F-35 fighters and may be subject to US sanctions and measures by NATO.