Turkish troops travelling in a convoy of 12 armoured vehicles have entered northern Syria in a new military operation.
Turkish news media reported that the vehicles carrying the troops crossed into Idlib province late on Thursday.
The development came after Turkey said it was sending troops into Syria to enforce a de-escalation zone in Idlib, which is largely controlled by the Hay'et Tahrir al-Sham (HTS) alliance.
Turkish media sources said the convoy included about 80 soldiers.
Local sources told Al Jazeera the troops were headed towards the western part of Aleppo province.
Al Jazeera's Hashem Ahelbarra, reporting from Antakya, near Turkey's border with Syria, said dozens of military vehicles have crossed into Syria.
"We know from different sources that the Turkish military is in the western outskirts of the province of Aleppo, but their final destination is going to be Idlib.
"It remains to be seen what will happen to the Hay'et Tahrir al-Sham fighters, the former al-Qaeda affiliate; are they going to put up resistance against this operation? Are they going to pull out and hand over their weapons?"
Civilians there have been living in fear of potential clashes between Turkish-backed opposition Free Syrian Army fighters and HTS.
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.
The Turkish army began setting up "observation posts" in Idlib province as part of its efforts to create a de-escalation zone, the military said on Friday.
"On October 12 (Thursday), we began activities to establish observation posts," the military said in a statement.
Turkey is facing many challenges as it moves deeper inside Syria, Ahelbarra said.
"First of all, Turkey needs to implement the de-escalation zone. They have to ensure that no party engages in any fighting in the near future," he said.
"The second challenge is that the Kurdish forces are operating not far from where the Turkish military is stationed inside Syria. Turkey has said in the past that it considers all Kurdish factions, particularly the SDF and the YPG, "terrorist" organisations, and that it will not allow them to advance further west towards the Mediterranean.
Source: Al Jazeera News