Russian President Vladimir Putin has bitterly condemned thedowning of a Russian jet on the Turkey-Syria border.
He described it as a "stab in the back" committed by "accomplices of terrorists".
Turkey says its jets shot at the plane after warning that it was violating Turkish airspace. But Moscow says it never strayed from Syrian airspace.
Nato is to hold an extraordinary meeting to discuss the incident at Turkey's request.
Mr Putin warned there would be "serious consequences" for Moscow's relations with Turkey.