The Kurdish YPG, released a video on Tuesday showing the underground tunnels that ISIS digs to launch sneak attacks.
Look inside the tunnels ISIS uses to launch sneak attacks in Raqqa
Some of the tunnels reportedly even have rooms and toilets.
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The video shows two rather large tunnels inside a captured, bombed-out mosque, from which the YPG claim that ISIS had been using.
"The barbaric group, aware of the YPG's sensitivity towards people's places of worship, and other historic sites, has been using [mosques] as bases to delay the liberation of Raqqa," text in the YPG video reads.
YPG-led SDF discovers Daesh (ISIS) tunnels inside mosque in eastern Raqqa
Former ISIS fighters have reportedly said that some of the tunnels are extremely complex, some even containing rooms, toilets and medical facilities.
A YPG commander recently said there are about 700 to 1,000 ISIS fighters left in Raqqa, and that the battle should be over in about 2 months.
This older Fox News video shows how intricate the tunnels can get: