Turkish President Tayyip Erdogan gestures as he addresses AK Party and Nationalist Movement Party (MHP) supporters during a rally for the upcoming local elections, in Istanbul, Turkey March 24, 2019. REUTERS/Umit Bektas

ISTANBUL (Reuters) - Turkey will not go back on the purchase of S-400 missile systems from Russia no matter what the United States says, President Tayyip Erdogan said on Sunday.

He made the comment in an interview with broadcaster TGRT Haber.

The United States could soon freeze preparations for delivering F-35 fighter jets to Turkey, officials told Reuters, in what would be the strongest signal yet by Washington that Ankara cannot have both the advanced aircraft and Russia’s S-400 air defense system.