03:04 - Source: CNN
What will be ISIS' downfall?

Watch the full interview on CNN’s “The Situation Room” at 5 p.m. EST.

Washington CNN —  

The man tapped to coordinate the U.S.-led coalition against ISIS told CNN there is an opportunity for broad cooperation in the fight, even as the countries involved struggle to define their roles.

“This is an opportunity,” Retired Gen. John Allen said Wednesday. “It’s actually an important moment where so many countries from so many different backgrounds share that view [that ISIS poses a threat to the region], that this is an opportunity to create partnership across those lines of effort that would achieve real effect.”

Gen. Allen sat down with CNN for an exclusive interview just before he headed overseas to meet with members of the coalition.

During that interview, they also discussed the role Iran’s government might play in taking on the terrorist organization, sometimes referred to as ISIL or the Islamic State.

“We’re not going to contemplate a bilateral coalition with Iran,” the retired Marine general said. “But Iran has deep interests and relationships in Iraq, and ISIL is a threat to Iran’s interests as well.”

Gen. Allen said Iran can play a constructive role providing support to Iraqis and “creating an opportunity for the new Abadi government to be a government of all Iraqis, not just of Shia Iraqis, not ultimately of Sunni or Kurdish Iraqis, but all Iraqis.”

One government that’s not welcome in the effort – Syria.

“Our policy is very clear and that there should be, in the end, in Syria a political outcome,” said Gen. Allen. But “[Syrian] President Assad won’t be part of it, frankly.”

Despite the administration’s insistence that it will not cooperate with the Assad regime, the U.S. military has been conducting airstrikes against terrorist targets inside Syria since early last week.

The U.S. is also undertaking efforts to arm and train moderate Syrian opposition forces, who are locked in a fight against both ISIS, the Assad regime, and a variety of other armed groups.

But the process of training those forces will not be a quick one.

“It could take years,” said Allen. “But the process for getting that unfolded is occurring right now.”

“Expectations need to be managed,” Allen added.

But then what will success look like in Iraq and Syria?

The endgame Gen. Allen envisions is this: “Territorially intact and sovereign Iraq, governed by the government in Baghdad, that governs all Iraqis, not just one sect, not just one confession.”

“And in Syria,” he continued,”we’re seeking to create the capacity within the Free Syrian elements and the Syrian opposition so that, first of all, they can defend themselves from the Assad regime and from the other al Qaeda oriented organizations in the battle space.” Gen. Allen believes that will give the moderate opposition room to achieve the long-sought “political solution.”

Coalition building is not new to General Allen. During his time in the military, he served as deputy commander in Iraq’s Anbar province and as deputy commander for U.S. Central Command. He was also the commander of ISAF forces in Afghanistan from 2011 to 2013.

There, he worked to build relationships with Sunni tribal leaders, known as the Anbar Awakening, which was credited with helping turn the tide against al Qaeda in Iraq.

He told CNN he is confident a similar rift will occur this time between Sunni tribes and ISIS.

“The one thing I know for sure is just as I learned by watching al Qaeda work on the ground in al Anbar in ‘07 is that there will come the time when ISIS cannot tolerate the tribal structure within ISIS territory because that tribal structure is in direct opposition to the full exertion of ISIS influence over the population, and ISIS will turn on the tribes as sure as the sun will come tomorrow.”

“So the tribes recognized this in a very real way,” Gen. Allen said, “and I think within their own capabilities we’re already seeing tribes that are rising up against ISIS. We’re already seeing tribes that are coordinating with the other elements within the Iraqi security forces to achieve effect against ISIS. And there are tribes out there ready to go.”