ANKARA, Turkey (AP) — Turkey’s foreign minister says his country could look “elsewhere” if the U.S. doesn’t deliver F-35 fighter jets.

Mevlut Cavusoglu also said in an interview with private NTV television Tuesday that Turkey could consider acquiring more Russian-made S-400s or other systems to meet urgent needs if it can’t purchase U.S. Patriot systems.

Turkey’s moves to buy the Russian S-400 technology have heightened tensions with Washington. U.S. Vice President Mike Pence warned that Turkey was risking its NATO membership and its participation in the F-35 program.

Cavusoglu said: “If F-35s are not delivered, I would be placed in a position to buy the planes I need elsewhere.”

He added that a new U.S. offer to sell Patriots was “more rational” than a previous offer, but still didn’t meet Turkey’s expectations.