ISIL was believed to have only 2,000–3,000 fighters up until the Mosul campaign, but during that campaign, it became evident that this number was a gross underestimate.
ISIL mentes kun at have 2.000-3.000 kæmpende indtil Mosul-kampagnen, men i løbet af denne kampagne blev det klart, at dette tal var en grov undervurdering.