“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.”
Source: How did 800 ISIS fighters rout 2 Iraqi divisions? | Military Times | militarytimes.com