Turkey’s foreign minister said Thursday his country won’t bow to “ultimatums” after the United States warned Turkey it was excluding it from the F-35 fighter jet program over its deal with Russia to purchase its S-400 missile defense system.

China’s made-for-export FC-31 warplane is making a big impression, as reports say international buyers are thinking of buying the stealth fighter jet, with Chinese military experts recommending on Tuesday that China try to seize these opportunities.

Russia said on June 11 that it plans to deliver its S-400 missile defense systems to Turkey in July, just days after Washington gave Ankara a deadline of July 31 to reverse the purchase or face the loss of subcontracting work on the U.S.-led F-35 fighter-jet project.