AL JAZEERA NEWS
The de-escalation zone forms part of an agreement reached between Turkey, which backs forces battling the government of President Bashar al-Assad, and Iran and Russia, which support his government.
Turkish media sources said the convoy included about 80 soldiers.
While their destination was not clear, local sources told Al Jazeera the troops were headed towards the western part of Aleppo province.
Al Jazeera's Hashem Ahelbarra, reporting from Antakya, along Turkey's border with Syria, said: "This is what we know so far: dozens of military vehicles have crossed into Syria.
"It remains to be seen what happens to the fighters who control Idlib province."
Civilians there have been living in fear of potential clashes between Turkish-backed opposition Free Syrian Army fighters and Hayat Tahrir al-Sham, an alliance of armed groups that controls Idlib.
A military build-up has taken place of late along Turkey's border with Syria, with the Turkish government supporting a campaign to secure opposition control over Idlib province.