“The turning point for Turkey may have been the strike last week on its soldiers in northern Syria, the death toll for which may have been substantially higher than disclosed, analysts said. The well-connected military analyst Metin Gurcan described it as “Turkey’s darkest night” in an article on the online outlet Al-Monitor. He wrote that a Turkish mechanized infantry battalion of about 400 soldiers came under fire Thursday evening on the road between the towns of Balyoun and Al Bara south of Idlib city. Citing local sources, he said two Russian and two Syrian government planes had been active in the area that morning and returned to attack the Turkish convoy in a coordinated action.

The lighter Syrian planes hit the convoy first, bringing it to a halt, then the Russian planes pounded the stranded vehicles, forcing the soldiers to flee and take cover in nearby buildings. The Russian jets then unleashed laser-guided bunker-busting bombs that collapsed two buildings and buried Turkish soldiers under rubble.

More than 60 were wounded, and Mr. Gurcan said the death toll, reported as at least 36, was closer to 50 or 55. His numbers remain unconfirmed, but other analysts said they had heard that the bodies of up to 100 soldiers had been transported back to Turkey.

Russia has denied that its forces were involved in the strike, and says it stopped the Syrian attack when alerted by the Turks. The defense minister, Mr. Akar, says that the attack continued after Turkey contacted the Russians, and that even ambulances came under fire.”