Vladimir Putin has bitterly condemned the downing of a Russian warplane on the Turkey-Syria border.
The Russian president described it as a “stab in the back” committed by “accomplices of terrorists”.
Turkey says its jets shot at the Russian warplane after warning that it was violating Turkish airspace. However, Moscow says it never strayed from Syrian airspace.
NATO held an extraordinary meeting at member Turkey’s request to discuss the incident.
Its Secretary-General, Jens Stoltenberg, has said allied assessment of the incident shows that the Russia warplane did fly into Turkish airspace.
One of the two crew members who ejected from the downed plane was killed by fire from the ground, the Russian military said. The fate of the other is unclear.
A Russian soldier was killed when the helicopter he was on came under fire during a search and rescue mission, a spokesman added.
Vladimir Putin warned there would be “serious consequences” for Moscow’s relations with Turkey.
Russian Foreign Minister Sergei Lavrov has said he was canceling his visit to Turkey, where he was due on November 25, over the incident.
He also advised Russians not to visit Turkey and said the threat of terrorism there was no less than in Egypt, where a bomb attack brought down a Russian passenger plane last month.
Vladimir Putin said the Su-24 was hit by an air-to-air missile fired by a Turkish F-16 while it was flying over Syrian territory.
He said the plane had been attacked “at a height of 6,000 meters [20,000ft], 1km from the border”.
It crashed into Syrian territory 2.5 miles from the border, he added.
The plane flew over a small piece of Turkey that projects into Syria that would have taken the jet only a few moments to fly over, correspondents say.
The two crew members ejected as their burning aircraft plunged into a Syrian hillside.
Video footage has shown what appears to be the dead body of one of the flyers, surrounded by armed rebels.
Another piece of video, obtained by a Turkish news network, has shown the pilots being shot at from the ground by unidentified rebels.