By vowing to "degrade and destroy" the Islamic State militants, U.S. President Barack Obama has laid out a goal that will certainly face a series of daunting challenges and could take years to accomplish.
"Degrading is relatively easy," said Austin Long, assistant professor of international and public affairs at Columbia University and a former adviser to the multinational force in Iraq, "It's the destruction part that’s very difficult."
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"You can continue with airstrikes. That would certainly be effective over time at degrading the organization over time, particularly as your intelligence picture gets better," Long said. "But there’s a real limit, particularly on how much damage you can do to an organization that is well institutionalized and as large as ISIS."
ISIS is thoroughly embedded in northern and eastern Syria and northern and western Iraq. It has thousands of combat-experienced fighters, is very well financed and well armed, and gains more adherents every day, said Peter Mansoor, the former executive officer to then general David Petraeus during the period of the Iraqi surge in 2007 and 2008
"So it’s not going to be an easy group to destroy, and it'll take a number of years to do so, absent direct involvement from U.S. ground forces, which is not in the cards," Mansoor said.
But Colin Clarke, an associate political scientist who specializes in insurgency and transnational terrorism at the Rand Corporation, said the most realistic goal should be containment, not destruction.
'Weaken, not obliterate'
"It should be enervate, to weaken, not obliterate," Clarke said. "It think that's not only more realistic but it's more achievable."
"I’m not sure you could actually ever really fully extirpate it," he said. "It's really about reducing it from a major challenge to a regional nuisance."
Clarke, along with Christopher Paul, wrote Paths to Victory: Lessons from Modern Insurgencies, a study of 71 counterinsurgencies since the end of the Second World War. In a piece for the Washington Post, both Clarke and Paul said the U.S would need to overmatch the insurgency, something continued airstrikes would help accomplish. But it also must hone in on ISIS's operational tools — money, weapons, intelligence, training and sanctuary — as well as the group's organizational tools: leadership, ideology, media recruitment and organizational structure.
Part of the strategy to combat ISIS would involve engaging in a hybrid war, one that combines conventional and irregular forces fighting together, Mansoor said.
The Iraqi army would need to be rebuilt into a competent fighting force, while the Kurdish Peshmerga forces would also need to be armed, trained and advised, all of which could take one to two years.
Training the Kurds, who have been seen as an effective force against ISIS, would take less time. However, the issue with the Iraqi army is leadership, Mansoor said, and it will take time to vet new leaders.
Around 10,000 to 15,000 U.S. troops would be needed in an advisory capacity, Mansoor estimated. But he added that hundreds of U.S. special forces troops would be needed on the ground to help call in airstrikes and make those attacks more effective, meaning that some American soldiers "would be in the thick of it."
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But that entire strategy is all predicated on the creation of a government in Baghdad that all sects, ethnicities and factions in Iraq can support, analysts say. Getting co-operation from the Sunnis, who for years were disenfranchized by the Nouri al-Maliki government, would be crucial to any kind of success. Yet with al-Maliki having recently stepped down as Iraqi prime minister, there's renewed hope that the new government would be more inclusive.
"Absent that I don't think any strategy will succeed," Mansoor warned.
The challenge of Syria
Syria poses another huge challenge, and a bit of a conundrum. The White House doesn't want to inadvertently be in a position of of directly or indirectly helping the Assad regime, but in order to do damage to ISIS, the U.S. will need to be able to strike in Syria.
"So how do you balance those objectives?" Long said.
One route is to arm and boost up the Free Syrian Army, seen as a relatively moderate group among the rebels fighting the Syrian government. But, as Mansoor observed, the group is currently "pretty much a wet noodle" in terms of strength and could take years to get into fighting form.
Regional co-operation would also be key. Mansoor suggested that Jordan and Turkey could provide bases for aircraft and special forces. But building such a coalition wouldn't be easy when it comes to determining what countries join and what roles they play.
"The region is still in flux and the dust really hasn't settled from the Arab Spring," Clarke said.
As well, the U.S need only turn to their recent military incursions to show the difficulties of defeating such groups.
"The U.S had over 100,000 troops on the ground in Iraq at on point and was conducting an all out offensive against ISIS predecessor al-Qaeda in Iraq and wasn’t capable of completely destroying it," Long said. And the Taliban in Afghanistan has been "degraded, degraded and degraded," yet it continues to rebuild.
"These campaigns can be quite open-ended even though you can inflict damage quite quickly," he said. "So destroying organizations like ISIS is going to be extremely challenging."