ISIS' rapid conquest through Iraq has caused major problems for defense planners trying to figure out strategies to help local security forces deal with the rapidly expanding terrorist group.
The big problem? Getting Iraqis to fight.
In recent ISIS attacks, such as on Mosul and Palmyra, security forces didn't fight and instead fled.
Iraqi security forces lost over 2,300 Humvee armored vehicles when ISIS overran the northern city of Mosul, Prime Minister Haider al-Abadi announced on Sunday.
"In the collapse of Mosul, we lost a lot of weapons," Abadi said in an interview with Iraqiya state TV. "We lost 2,300 Humvees in Mosul alone."
Its not only a hugely expensive loss - it has also notably boosted ISIS's capabilities.
The latest batch of vehicles delivered to Iraq featured increased armor, machineguns, and grenade launchers that were estimated to cost $579 million. And that's just for 1000 vehicles.
The total value of the captured vehicles in Mosul was well north of $1 billion.
The battle for Mosul, Iraq's second largest city, began late on June 9th, 2014, and saw Iraqi forces lose the city the following day.
In addition to the armored vehicles the militants gained ample arms, ammunition and other equipment when multiple Iraqi divisions abandoned gear and shedded their uniforms as they ran away from the oncoming attackers.
ISIS has used the captured Humvees in subsequent fighting, even rigging some with explosives for suicide bombings, their weapon of choice.
Iraqi security forces backed by Shiite militias had gained ground from ISIS in Diyala and Salaheddin provinces, located just north of Baghdad.
But that quickly reversed in mid-May when ISIS overran Ramadi, the capital of Anbar province, west of Baghdad, which Iraqi forces had been holding for more than a year.