A Russian marine has been killed on a helicopter mission to rescue the crew of a jet downed by Turkey near the Syrian border on Tuesday, according to a BBC news report.
He died when his helicopter came under fire from rebels in northern Syria, where the plane crashed.
Rebel fire from the ground killed one of the jet’s two crew members after they ejected.
The head of Nato said it stood in solidarity with Turkey as the Kremlin warned of “serious consequences”.
US President Barack Obama later assured his Turkish counterpart, Recep Tayyip Erdogan, in a phone call of US support for his country’s right to defend its sovereignty.
The White House said both presidents had agreed on the importance of de-escalating the situation.
Turkey said the jet had strayed into its airspace but Russian President Vladimir Putin insisted the Su-24 had been hit by an air-to-air missile while flying over Syrian territory.