ANKARA, Turkey — Turkey shot down a Russian fighter plane Tuesday — a long-feared crisis in Syria’s civil war and apparently the first time a NATO member has downed a Russian plane in a half-century.

Russian President Vladimir Putin called Turkey’s action a “stab in the back by the terrorists’ accomplices” and warned of “significant consequences.” At Turkey’s request, NATO’s governing body called an emergency meeting.

Turkish Prime Minister Ahmet Davutoglu insisted his country has the right to take “all kinds of measures” against border violations, and called on the international community to work toward “extinguishing the fire that is burning in Syria.”

Turkey said the Su-24 ignored several warnings that it was nearing, then intruding, into Turkish airspace. Russia insisted the plane stayed over Syria, where it was supporting ground action against rebels.

“We will never tolerate such atrocities as happened today and we hope that the international community will find the strength to join forces and fight this evil,” Putin said.

Rebels said they fired at the two parachuting pilots as they descended, and that one had died. A rebel spokesman said they would consider releasing the body in exchange for prisoners held by Syria. The fate of the second pilot was not immediately known.

Despite harsh words, some analysts believe that Russia and Turkey have reasons not to let the incident escalate.

“Relations have been very strained between Russia and Turkey of late so Moscow will be trying its utmost to contain the damage this might cause,” said Natasha Kuhrt, lecturer in International Peace and Security at King’s College London.

“It’s a serious incident in anybody’s book,” added Ian Kearns, director of the European Leadership Network, a London think-tank.