Damascus has deployed a new anti-missile system along the Syrian-Turkish border. The system will be able to intercept Turkish jets should they invade the country's airspace.
Previously, Turkey let Al-Qaeda militants cross the border: the militants had seized the border town of Kesab, mostly populated by Armenians. The Russian Foreign Ministry condemned the capture of Syrian civilians.
Not that long ago, Turkish air defense down a Syrian plane that illegally crossed the country's airspace.
Last week, Turkey banned YouTube video hosting service after the appearance of the video, in which senior Turkish officials discuss a possible invasion of Syria.
Turkish President Erdogan personally ordered to shoot down the Russian Su-24 fighter jet on November 24, 2016, when the aircraft was on a combat mission in Syria