Following this, many Turkish F-16 warplanes have flown over the country's capital Ankara on Monday and Tuesday to test its new Russian S-400 missile defenses. Ankara's purchase of the S-400s has been a major factor souring relations with the United States, which says the system is not compatible with NATO defenses and poses a threat to Lockheed Martin's F-35 stealth fighter jets. It is expected that Ankara will deploy the S-400 from next year's spring after the system is fully installed and personnel training process is completed.
