Acting U.S. Defense Secretary Mark Esper warned his Turkish counterpart on Wednesday that Ankara’s purchase of Russia’s S-400 air defense system would not only end Turkey’s role in the F-35 fighter jet program, it would also hurt the Turkish economy due to ensuing U.S. sanctions, a senior U.S. official said.

“The secretary was very firm, once again, that Turkey will not have both the S-400 and the F-35. And if they accept the S-400 they should accept ramifications not only to the F-35 program but also to their economic situation,” said the senior U.S. defense official, speaking on condition of anonymity, after the U.S.-Turkey meeting on the sidelines of NATO gathering in Brussels.