A large Turkish military convoy entered the northwestern Syrian province of Idlib, reports said Monday.
The 50-vehicle convoy was accompanied by the Syrian National Army (SNA) troops, Ihlas News Agency (IHA) reported.
Sources said Turkey was deploying special forces to the border with Syria to strengthen its troops standing guard.
The Russia-backed Bashar Assad regime has been on the offensive since December to capture and reopen a strategic highway held by the opposition since 2012, despite a cease-fire deal brokered late last year between Russia and Turkey.
Regime forces captured the key town of Maaret al-Numan from the rebels last Wednesday, and have now set their sights on the town of Sarqeb. The strategic highway passes through both.
Idlib province is home to some 3 million people, many of them displaced from other parts of Syria in earlier bouts of violence. The U.N. has estimated that 390,000 Syrians have been displaced there over the past two months – 315,000 in December and 75,000 in January.
Turkey already hosts 3.5 million Syrian refugees, and the current wave of violence in Idlib has raised concerns about a new surge in displaced civilians fleeing toward the Turkish border.