Turkish and Russian military elements performed the 13th joint patrol along a key highway in Idlib, northwestern Syria, the Turkish National Defense Ministry said on Thursday, according to Anadolu Agency.

“Within the framework of TUR-RF Agreement/Protocol, the 13th TUR-RF Combined Land Patrol on M-4 Highway in Idlib was conducted with the participation of land and air elements,” the ministry said in a tweet.

The M4 highway, also known as the Aleppo-Al Hasakah road, is about 30 kilometers (19 miles) from Turkey’s southern border.

The twelfth joint patrol was carried out on May 20.

This March, Ankara and Moscow agreed on a protocol urging parties to “cease all military actions along the line of contact in the Idlib de-escalation area.”

The protocol said joint Turkish-Russian patrols would begin on March 15 along the M4 highway from the settlement of Trumba — 2 km (1.2 miles) to the west of Saraqib — to the settlement of Ain al-Havr.

Idlib has long been under siege by Assad regime forces and its allies, and previous cease-fires for the region were plagued by violations.

Turkey has worked to protect the local civilian population as well as rid the wider region of terrorist elements.