Ankara has not received an ultimatum from Washington over the S-400 deal, Turkish Defense Minister Hulusi Akar said in an interview with the Turkish channel Haberturk.
Akar's comments come amid reports that the United States has put forward an ultimatum to Turkey, threatening to kick Ankara out of the F-35 fighter jet programme if the Turkish government does not abandon the Russian missile defence systems.
The minister stressed that he would not comment on the "assumptions" when asked how Turkey would act if the United States imposed sanctions on Ankara.
"We are acting in full compliance with the commitments we have undertaken," Akar added, while emphasising that Turkey has fully paid for the delivery of F-35 fighters from the US, and Turkish pilots are already training on the new jets.
Meanwhile, Reuters cited two unnamed sources with knowledge of the situation as claiming that Washington is considering suspending training for Turkish pilots as the two countries have been at loggerheads for months.
Last week, 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".
The United States has, on a multitude of occasions, claimed that the S-400s are incompatible with NATO military equipment and alleged that the Russian air defence systems pose a threat to the F-35s.
Ankara, in turn, has insisted that the purchase of those weapons is its sovereign affair and has excluded the possibility of abandoning plans to complete the purchase.
As Turkey has consistently refused to abandon the deal, Washington has threatened to withhold the sale of the stealth fighters to Ankara, or to slap it with sanctions under the 2017 Countering America’s Adversaries Through Sanctions Act (CAATSA).
Russia and Turkey signed a $2.5 billion loan agreement for the shipment of a total of four batteries of S-400 systems in December 2017. The first delivery is set for July 2019 and will proceed as scheduled, according to Turkish officials.