Who is ISIS, why has Iraq's army crumbled, and how can the United States help? Three experts discuss these and other issues during a Washington Institute Policy Forum.

Watch clips from the event above or view the full Policy Forum on YouTube.

On June 13, Michael Knights, James Jeffrey, and Aaron Zelin addressed a Policy Forum at The Washington Institute. Knights, a Lafer Fellow with the Institute, has worked extensively with local military and security agencies throughout Iraq. Jeffrey is the Institute's Philip Solondz Distinguished Visiting Fellow and former U.S. ambassador to Iraq. Zelin is the Institute's Richard Borow Fellow and an expert on the jihadist groups currently waging war in Iraq and Syria. The following is a rapporteur's summary of their remarks.

MICHAEL KNIGHTS

The battlefield in Iraq is evolving in two important ways. First, the Islamic State of Iraq and al-Sham (ISIS) has attained great strategic depth in terms of the distance that reconstituted Iraqi forces would need to travel to retake key areas -- namely, 350 kilometers of contested terrain from Baghdad north to Mosul. Yet the jihadist group's east-west strategic depth is as small as 10-30 kilometers in places, underlining the major role that Kurds could play. Key ISIS strongpoints are within striking distance of Kurdish forces, making it vital to bring them fully into this fight. Accordingly, Baghdad must offer the Kurdistan Regional Government a solution on at least some of the revenue-sharing and oil issues that have divided them. The Kurds are already taking casualties now that the Iraqi army has abandoned certain areas. They have also suffered depredations at the hands of radical Islamists in the past, and will not tolerate a major ISIS control center within an hour's drive of Erbil, the KRG's economic capital.

Second, the ISIS offensive has created an acute morale problem that must be addressed. Around 60 of 243 Iraqi army combat battalions cannot be accounted for, and all of their equipment is lost. It will be a mammoth task to put these units back together and rearm them. The United States will once again become the arsenal of democracy, but this time Iraq will likely have to foot the bill rather than the U.S. taxpayer. Just as important, the defeated army needs to be turned around. The Iraqis have many military achievements from which to draw inspiration, particularly the defeat of al-Qaeda in 2008, but regrouping will still be tremendously difficult. This is where the United States can play a key role. It would not take many American advisors, inserted at the divisional level and above, to help Iraqi forces pick themselves up and dust themselves off. The key is to take baby steps -- win small, easy battles first to rebuild confidence for the larger battles farther north.

Although introducing U.S. airpower into the conflict would not be a silver bullet, there are many instances in which a little bit of it could go a long way in facilitating Iraqi operations and boosting morale. This effect was seen in parts of Libya, where French airstrikes turned the military situation around. Air operations in Iraq would also require a Joint Special Operations Task Force on the ground.

At this stage, it is not difficult to imagine Iraq going the same way as Syria, with northwestern Iraq coming to resemble Raqqa, Syria, where ISIS is in control perhaps semipermanently. And if Washington does not give the Iraqi government sufficient backing, Baghdad could turn to another country with a recent track record of protecting its allies: Iran. The Islamic Republic and its Hezbollah proxy have demonstrated their capabilities by bolstering the Assad regime in Syria. Some in the Iraqi government believe they need to use the same formula that Assad has, and maybe some of the same helpers as well -- namely, the Islamic Revolutionary Guard Corps and Shiite militias.

Accordingly, the United States needs to make a credible gesture of military support immediately. Although U.S. officials should play hardball with the Iraqis about coming to a political reconciliation deal between the country's various Arab and Kurdish factions, Washington must still make a baseline determination about what is needed to stabilize the current crisis. America must commit to the defense of Iraq, not leave it for ISIS or the Iranians.

JAMES JEFFREY

Last September, President Obama told the UN General Assembly that four critical issues would require all elements of U.S. power to address in the near term: securing oil lines, combating terrorism, standing by our allies, and weapons of mass destruction. The first three are in play in Iraq right now. The largest-ever concentration of al-Qaeda-style jihadists is now operating in western Iraq and Syria, with ISIS the nastiest of the bunch. Oil prices are spiking, and although Iraq's oil fields in the Kurdish north and Shiite deep south are not directly threatened at the moment, grave instability elsewhere in the country and political deadlock in Baghdad will greatly inhibit its vast hydrocarbon potential. In short, U.S. interests are very much at stake, and speed is of the essence.

Six issues will be particularly crucial in the next few days. First and most important is whether ISIS -- which has already seized almost all of Iraq's Sunni Arab areas -- will now carry out its threat to move on Karbala, Najaf, and Baghdad. The group certainly has the capability to do so. Given its longstanding presence in the mixed Sunni-Shiite areas north and south of Baghdad, it could cut off the city. U.S. forces faced a similar situation in summer 2004 when they were fighting al-Qaeda and Shiite militias. Even with large numbers of troops and overwhelming airpower, it was a very tough situation.

Alternatively, if ISIS decides to stay where it is, a classic counterinsurgency will likely unfold. In that scenario, American troops would not liberate the Sunni areas of Iraq -- the Kurds, Sunnis, and Shiites would have to do so, or nobody. In theory, Washington could provide logistics, training, and overwhelming firepower for that fight, but it is unlikely to do so, nor should it. If the Iraqis will not fight for their own country, America should not get involved. Yet President Obama would face a very different decision if ISIS pushes toward Baghdad.

Second, can the largely Shiite Iraqi army and Shiite militias hold together? If they can maintain their cohesion, use their vastly superior firepower and numbers effectively, and hold the territory where their families live, Washington will not have to worry about ISIS besieging Baghdad -- the Iraqis will be able to push the group back themselves and keep the roads open. It will be messy, but they can do it. Their ability to hold together sufficiently is still a big if, however. Alternatively, if ISIS is able to reach Baghdad, Iraqi forces are strong enough to avoid being overrun but may be unable to maneuver, use firepower, or coordinate effectively, resulting in a de facto siege.

Third, the Kurds are now sitting on a new "Green Line," the boundary demarcating their region of Iraq. They have two choices depending on how events turn out: they can push ISIS back by exerting their considerable military pressure on the group, or sit back and witness the potential disintegration of Iraq, Iranian domination in the south, and a jihadist threat at their doorstep.

Fourth, if Baghdad or other cities important to Shia Islam are besieged and no other party intervenes, it is difficult to imagine Iran not acting. The consequences of the Sunni-Shiite Gotterdammerung that could emerge from such intervention are beyond calculation.

Fifth, Turkey is in a very awkward position given that eighty of its citizens are hostages in Mosul, including its entire consulate. Yet the Turks still have major military capabilities and very close ties with the Kurds, so the possibility of their involvement cannot be discounted.

Sixth, the nature of the U.S. response will be crucial. The president gave a somewhat mixed message in his June 13 remarks, pledging to first consult with Congress about his options. While he ruled out ground forces, what he meant were major ground forces, not forward air-controller teams or trainers, for example. In fact, some military advisors are already on the ground. As for airstrikes, the president did not make a commitment one way or the other. Whatever the case, if ISIS advances on Baghdad, potentially drawing in Iran, the United States will need to act quickly. The president would also be wise to use the prospect of U.S. intervention as leverage to push for an inter-Iraqi political deal. Yet Washington has failed to get that deal done despite four years of trying, so if the president intends to keep U.S. planes grounded until reconciliation is achieved even as ISIS moves forward, then other actors will shape the playing field.

AARON ZELIN

The ISIS takeover of Mosul did not come out of nowhere. The group has been reemerging since April 2013, when it officially broke away from al-Qaeda and began expanding from Iraq into Syria. While the 2008 U.S. surge and Iraqi sahwa (awakening) movement pushed ISIS back, it was not defeated. Because of its new operational space in Syria, it acquired new manpower and resources to pour southward, and foreign jihadists who originally came to fight in Syria have been deploying to Iraq for about six months. Since April 2013, the rate of violence in Iraq has been three-and-a-half times higher than in the previous four-and-a-half years. ISIS has gained additional manpower from jailbreaks, such as the estimated 500 prisoners who escaped from Abu Ghraib last July. Many were veterans of the fight against the surge/sahwa, and their experience has raised the competency level of ISIS operations, as seen in this year's takeover of Fallujah and parts of Ramadi.

Another new ISIS tactic is the use of hearts-and-minds strategies to make itself more acceptable to locals. To be sure, ISIS views the territory it has seized in Iraq and Syria as part of its "Islamic state," forcing residents to pledge bayat (allegiance) or suffer the consequences. On June 15, it released a charter in Mosul detailing new rules and punishments (e.g., the obligation to pray five times a day) and declaring that it would destroy shrines and graves that it considers polytheistic. In fact, the group has already provided a case study for such behavior via its rule in Raqqa, Syria, where it began by putting up billboards highlighting pietistic themes. At the same time, however, it reached out to notable tribal figures to stave off a popular backlash. ISIS also has a highly sophisticated bureaucracy: it operates sharia courts, carries out public works, provides religious schooling and services such as food kitchens, and maintains a vigilante force. Parts of Iraq may soon look like this as well.

Going forward, ISIS will likely consolidate its strength using the estimated $425 million it seized from Mosul's central bank, buying people off and reinforcing the Syrian front. Even so, key questions remain regarding its capabilities. First, is the group stretched too thin? ISIS has around 7,000-10,000 members, but they are now spread out from the Aleppo countryside to Mosul. Can they hold that much territory, particularly when so many locals resent them? Tribal leaders in Ramadi and Mosul have stated that they intend to resist the jihadists.

These questions aside, the group's Islamic state is already a reality. ISIS members can now readily crisscross provinces within this "state," which could make it difficult to completely dislodge them from Iraq and Syria or prevent them from consolidating control. Meanwhile, steady victories are raising the group's prestige and attracting more foreign fighters. ISIS is a sophisticated and well-organized force, and it will be much more difficult to dislodge than any previous movement.

This summary was prepared by Kelsey Segawa.