Inside ISIS' mind-blowing network of underground tunnels, filled with drugs and ammunition

Over the past year, ISIS has constructed an astonishing network of underground tunnels in the town of Sinjar, Iraq, which they seized in 2014.

The Associated Press obtained remarkable footage of the tunnels, which were packed with US-made ammunition, prescription drugs, and copies of the Quran.

Thirty to 40 tunnels were found in total, each wired with electricity and each with their own sleeping quarters. The extremist group had carved out a small community in its underground network of tunnels.