Turkish President Recep Tayyip Erdogan has rejected the Pentagon's ultimatum on Ankara's purchase of the S-400.
"The S-400s we're buying are not connected to the security of NATO, the United States or the F-35 in any way," Erdogan said, speaking at a rally in Diyarbakir on Saturday, according to Turkish television channel TRT.
"The reasons for our purchase of these systems are obvious," the president added, stressing that Ankara had nothing to hide regarding the intended use of the S-400s.
Erdogan's remarks follow on comments Friday by US Department of Defence spokesperson Charlie Summers that "there would be grave consequences in terms of" the US-Turkish "military relationship, and the Patriots and the F-35s" if Ankara went ahead with the delivery of the S-400s. "They will not get the F-35s if they take the S-400," Summers said.
This week, a senior Pentagon general urged lawmakers from the Senate Armed Services Committee to block US deliveries of the F-35 jet to Ankara if it doesn't abort its purchase of the S-400s, warning that the Russian system "presents a problem to all our aircraft, but specifically the F-35."
Russia and Turkey penned a $2.5 billion contract on four battalions of S-400s in late 2017, with Ankara set to become just the fourth country to possess the system after Russia itself, Belarus and China when deliveries begin in October. Designed to stop enemy air aircraft, drones, cruise and ballistic missiles, the S-400 is the most advanced mobile air defence system in Russia's arsenal.