The tunnels, which include rebar at their entrances and concrete walls inside, also feature deep pits nearby, which are thought to be used for pedestrian access or ventilation.
The Free Dawn Operation, launched in December, first liberated the town center of Tel Rifaat from the PKK/YPG.
With the liberation of Manbij, the region, which had become the largest terrorist stronghold west of the Euphrates River, was cleared of PKK/YPG control.
