The extremist group seizing vast swaths of Iraq this week is most likely fielding a small force of less than 1,000 fighters equipped with little more than small-arms weaponry and soft-shelled pickup trucks.
But the Islamic State of Iraq and Syria, or ISIS, apparently has routed an estimated 30,000 Iraqi Army soldiers who were trained by the U.S. military and given billions in sophisticated American military equipment.
The stunning outcome reflects widespread desertions among the Iraqi units in the north as well as the Sunni-Shiite sectarian tensions that underlie the military battles, experts say.
“It’s a relativity small force that managed to take the city [of Mosul], and it’s shocking that they were able to do that,” said Charlie Cooper, who studies Islamic extremism for the Quilliam Foundation in London.
“To me, that suggests there is collusion or at least deliberate capitulation on the part of Sunni tribes in western and northern Iraq,” Cooper said. “It’s likely that this happened because Sunni tribes in the area let it happen.”
Experts say ISIS totals no more than 10,000 fighters throughout Iraq and Syria, while the force that specifically seized the city of Mosul this week probably totaled about 800 fighters. That force overpowered two Iraqi Army divisions totaling about 30,000 troops.
“Clearly, the Iraqi forces in the north lack cohesion and a will to fight,” said Jeff White, a former intelligence analyst with the Defense Intelligence Agency who is now a defense expert with the Washington Institute think tank.
In terms of weaponry, ISIS has small arms and civilian-style pickup trucks with mounted crew-served weapons, mainly heavy machine guns such as Russian-made Dushkas, and also a limited supply of 23mm anti-aircraft weapons that they are using for direct fire, White said.
On the other side, the Iraqi army is awash in about $15 billion in U.S. gear transferred since 2005, including IA-407 helicopters, M-1 Abrams tanks, C-130 fixed-wing aircraft and 300 hellfire missiles, Pentagon officials say.
While the ISIS force has limited manpower, it may be joining up with other elements of the Iraqi insurgency that U.S. troops fought for years, such as the more sectarian Sunnis who once controlled the Iraqi Army under Saddam Hussein’s Ba’ath Party.
“Were hearing a lot about former Ba’athists coming out of the woodwork and working with [ISIS], and that could give them a lot more capability,” White said.
Until now, virtually all the territory seized by ISIS — portions of Anbar province in the west and the city of Mosul in the north — have a population majority that is Sunni Arab. Reports suggest ISIS fighters are moving south toward Baghdad, which has a large Shiite population.
“The Iraqi army units in the Baghdad area are presumably better trained, more reliable, more cohesive. One question is: Is that true? Does the government actually have Army elements it can rely on?” White said.
“On the ISIS side, the question is going to become one of force-to-space: Can they really keep pushing with a snowball effect? Or at some point are they going to actually come up against an effective force that brings this offensive to a halt?” White said.
One former senior U.S. commander in Iraq who spoke on condition of anonymity agreed that an important underlying problem stems from the current Shiite-led Iraqi government’s poor treatment of its Sunni minority in the north and west.
“It appears that three and a half years of highly sectarian and increasingly authoritarian actions undid the important reconciliation component of the strategy during the Surge and beyond, leaving Sunni Arabs once again feeling marginalized by the Shia-led government in Baghdad,” the former senior commander told Military Times.
That discontent, he said, has intensified inside the Iraqi military command as the Iraqi civilian government has replaced some Sunni military leaders with Shiites, undermining “the effectiveness and cohesion of the Iraqi army,” the former commander said.
The seizure of Mosul this week, along with parts of Anbar province several months ago, reflects in part a course change in the so-called “Awakening” movement, which the U.S. military fostered in 2006 and 2007, when local Sunni tribes in Anbar turned against the extremists in their midst and allied with the U.S. military.
“It’s as if this is a reversal of the [Awakening],” Cooper said.