By SELCAN HACAOGLU and ELIZABETH A. KENNEDY
Syria says it shot down a Turkish military plane that entered Syrian air space, and Turkey vowed to "determinedly take necessary steps" in response.
It was the most clear and dramatic escalation in tensions between the two countries, which used to be allies before the Syrian revolt began in March 2011. Turkey has become one of the strongest critics of the Syrian regime's brutal response to the uprising.
Late Friday, Syria's state-run news agency, SANA, said the military spotted an "unidentified aerial target" that was flying at a high speed.
It said a Turkish military plane in Syrian airspace was "dealt with according to laws observed in such cases."
Turkey issued a statement saying Syrian forces downed the plane and that the two Turkish pilots remain missing.