The Turkish military discovered a 30-meter tunnel and a concrete factory during a security sweep in Syria's northwestern Afrin region, which it and the Free Syrian Army (FSA) recently liberated from the PKK's Syrian affiliate Democratic Union Party's (PYD) People's Protection Units (YPG) militia. The concrete plant was a production base for concrete blocks built by YPG terrorists.

Turkey launched Operation Olive Branch on Jan. 20 to clear the YPG from Afrin, amid growing threats from the region.On March 18, Turkish-backed troops liberated the city center of Afrin, which had been a major center for the YPG since 2012.

Afterward, the Turkish military began security sweeps for mines, improvised explosive devices and hideouts to wipe out any traces of terrorism so residents can resume their normal lives.

During a search, forces found a concrete plant used by the YPG to build tunnels and fortifications in Afrin. The military also found tunnels and buildings made at the plant. The 30-meter tunnel was constructed with concrete blocks installed in wide holes. The YPG burned down construction equipment to prevent drones from collecting images.

Despite the recent discovery, questions over who provided the construction materials, equipment and raw materials for the plant or from where they came remains unknown.

The concrete plant in Afrin was not the only one under YPG control. Last month, Daily Sabah reported that the current case of French cement giant Lafarge's plant in northern Raqqa, which was seized by the YPG with the support of the U.S., and is currently under YPG control, begs the question regarding the supply source for the YPG's concrete tunnels and towers. The uncertainty regarding the current status continues to raise questions regarding Ankara's security concerns as the area is now controlled by the YPG.

Several reports also claim that the plant is currently used as a U.S. military base. The Lafarge plant in northern Raqqa and close to Kobani is located approximately 200 kilometers east of Afrin.