US officials have called Turkey's planned purchase of S-400 missile defense system "deeply problematic".
Turkish President Tayyip Erdogan said on Saturday that the purchase of S-400 defence systems from Russia was a done deal, adding that Ankara would also jointly produce S-500 defence systems with Moscow.
US officials have called Turkey's planned purchase of the S-400 missile defense system "deeply problematic," saying it would risk Ankara's partnership in the joint strike fighter F-35 program because it would compromise the jets, made by Lockheed Martin Corp.
However, Erdogan told a televised question and answer session with university students in Istanbul that Turkey had carried out technical work and found that such a problem did not exist.
"They (the US) are passing the ball around in the midfield now, showing some reluctance. But sooner or later, we will receive the F-35s. (The US) not delivering them is not an option."