ANKARA/BEIRUT: Turkey promised on Saturday to do "whatever necessary" in response to Syria's shooting-down of a Turkish fighter, but did not immediately contest an assertion by Damascus that the jet had been in its airspace at the time. The downing of the aircraft, at a point close to the sea borders of both countries, provided a demonstration of Syria's formidable Russian-supplied air defenses; one of the many reasons for Western qualms about any military intervention to halt bloodshed in the country. Ankara's once-friendly relations with Damascus had already turned icy over President Bashar al-Assad's violent crackdown on a 16-month-old revolt, but signals from both sides suggested neither wanted a military confrontation over the incident. "It is not possible to cover over a thing like this, whatever is necessary will be done," Turkish President Abdullah Gul said, according to state news agency Anatolia, adding that Ankara had been in tele...