ANKARA: Turkeys defense minister said it was preparing for potential U.S. sanctions over its purchase of Russian S-400 missile defense systems, even while he said there was some improvement in talks with the United States over buying F-35 fighter jets.

Turkey and the United States have been at odds on several fronts including Ankaras decision to buy the S-400s, which cannot be integrated into NATO systems. Washington says it would jeopardize Turkeys role in building Lockheed Martin F-35 fighter jets, which it says would be compromised by S-400s.