General Najim al-Jabouri, a former mayor of Tel Afar, which is a little more than 31 miles from Mosul, told The Daily Beast the bases seized by ISIS this week would provide the group with even more heavy weapons than they currently control. “The Iraqi army left helicopters, humvees, cargo planes and other heavy machine guns, along with body armor and uniforms,” the general, who is now a scholar at the National Defense University, said. He said he was able to learn about the equipment from soldiers and other politicians in and around Mosul with whom he keeps in touch.

General Najim is not alone in this assessment. Jack Keane, a retired four-star Army general who was a key adviser to General David Petraeus during the counter-insurgency campaign in Iraq in 2007 and 2008 known as the surge, said ISIS has now established itself as a formidable military force.

“This organization has grown into a military organization that is no longer conducting terrorist activities exclusively but is conducting conventional military operations,” he said. “They are attacking Iraqi military positions with company- and battalion-size formations. And in the face of that the Iraqi security forces have not been able to stand up to it.”