IRBIL, Iraq - Under the Iraqi town of Sinjar, Islamic State militants built a network of tunnels, complete with sleeping quarters, wired with electricity and fortified with sandbags. There, they had boxes of U.S.-made ammunition, medicines and copies of the Quran stashed on shelves.
The Associated Press obtained extensive video footage of the tunnels, which were uncovered by Kurdish forces that took the city in northwestern Iraq earlier this month after more than a year of IS rule.
"We found between 30 and 40 tunnels inside Sinjar," said Shamo Eado, a commander from Sinjar from the Iraqi Kurdish fighters known as peshmerga. "It was like a network inside the city."
"Daesh dug these trenches in order to hide from airstrikes and have free movement underground as well as to store weapons and explosives," Eado said using an Arabic acronym for the Islamic State. "This was their military arsenal."
The video, shot by a freelancer touring the town with Kurdish fighters, showed two tunnels running several hundred yards, each starting and ending from houses, through holes knocked in walls or floors.
The narrow tunnels, carved in the rock apparently with jackhammers or other handheld equipment, are just tall enough for a man to stand in. Rows of sandbags line sections of the walls, electrical wires power fans and lights, and metal braces reinforce the ceilings. One section of the tunnel resembled a bunker. Dusty copies of the Quran sit above piles of blankets and pillows. Prescription drugs - painkillers and antibiotics - lie scattered along the floor.
In another part of the tunnel, footage shows stocks of ammunition, including U.S.-made cartridges and bomb-making tools.
IS has been digging tunnels for protection and movement throughout the territory it controls in Iraq and Syria, even before the U.S.-led coalition launched its campaign of airstrikes against the group more than a year ago. "This has been part of ISIS' strategy from the very beginning," said Lina Khatib a senior research associate at the Arab Reform Initiative, a Paris-based think-tank. "ISIS has been well prepared for this kind of intervention."
The Islamic State took control of Sinjar in August 2014, killing and capturing thousands of the town's mostly Yazidi residents. Yazidis, a religious minority with roots that date back to ancient Mesopotamia, are considered heretics by the Islamic State. Hundreds of women are thought to still be in IS captivity. Those who have escaped say many Yazidi women are forced to convert to Islam and marry IS fighters.