With the Islamic State’s strongholds in Mosul and Raqqa under siege, the U.S. and its allies soon will face a different problem: how to track and contain the thousands of foreign fighters who have flocked to the jihadi movement and threaten to scatter to the winds to create mayhem back home.
The terrorist group’s prolific propaganda arm has gone so far as to tell its followers to abandon battlefields in the Middle East in favor of operations elsewhere, and it’s not clear that the Pentagon has a plan to deal with the next phase of the war.
U.S. defense officials estimate that roughly 60,000 fighters loyal to the Islamic State, or ISIS or ISIL, have been killed in the two years since the group’s blistering campaign across North Africa and the Middle East. But thousands more have fled those battlefields and returned as combat-hardened extremists to over 120 countries around the globe.
The foreign fighter threat is “the most ethnically diverse, sociologically diverse, nonmonolithic problem we have seen so far,” Army Lt. Gen. Michael Nagata, head of strategic operational planning at the National Counterterrorism Center, said this month.
“Just identifying the nature and scope of the problem is unfinished work together, but it is, I think, inarguably the largest foreign terrorist fighter challenge the world has seen in the modern age,” he said during a speech in Washington.
An analysis by the Soufan Group in late 2015 tracked how thousands of foreign fighters had flocked to the Middle East to join the Islamic State’s struggle and to protect the self-proclaimed “caliphate” there.
An estimated 5,000 fighters were from Western Europe, and nearly 300 were from North America. The question of the security threat posed by returning foreign fighters was a major focus of a March summit that the Trump administration organized for nearly five dozen nations that are part of the U.S.-led anti-terror coalition.
“We don’t want to see [the Islamic State] re-emerge elsewhere in the world; otherwise, we’ll be back in a few years’ time talking about how to defeat a caliphate in the southern Philippines,” Australian Foreign Minister Julie Bishop told Sky News after the summit.
FBI Director James B. Comey and Homeland Security Secretary John F. Kelly have issued public warnings about the threat posed by returning fighters. Mr. Kelly said coalition victories against the Islamic State overseas present a new security headache in the U.S.
“The expectation is that many of these ‘holy warriors’ will survive, departing for their home countries to wreak murderous havoc,” Mr. Kelly said in a speech Tuesday.
The numbers of battle-hardened Islamic State fighters could increase as U.S.-backed Syrian forces continue to drive jihadis from their safe havens in Raqqa and elsewhere.
U.S. and coalition forces reportedly launched an air assault with members of the Syrian Democratic Forces, or SDF, the group of Arab and Kurdish militias battling the Islamic State in the country, against the group’s positions near Deir-i-Zour.
Targeting Islamic State weapons depots in the eastern suburbs of the city, U.S. helicopters dropped SDF fighters early Monday, according to regional reports. It was the second such operation executed by Syrian forces in as many months.
Pentagon officials say Islamic State leaders, including “caliph” Abu Bakr al-Baghdadi, have begun to flee Raqqa for the group’s safe havens in Deir-i-Zour. The southern Syrian city could be the jumping-off point for a mass exodus by Islamic State fighters as coalition forces tighten the noose around Raqqa.
The foreign fighter threat is not limited to the Islamic State, one regional analyst said.
“We have a dispersed ISIS and a still-potent al Qaeda network to reckon with, and we may even see something of a reconciliation between the two groups,” said Thomas Sanderson, director of the Transnational Threats Project at the Washington-based think tank Center for Strategic and International Studies. “These developments point not to a lessening of the foreign fighter threat, but possibly to a heightening of the danger posed by them.”
Iraqi Vice President Ayad Allawi said Monday that the Islamic State and al Qaeda, once bitter rivals with diametrically opposed strategies for waging religious war, have begun discussing an alliance. “There are discussions and dialogue” between the Islamic State’s al-Baghdadi and al Qaeda leader Ayman al-Zawahri, via envoys and messengers from the terrorist groups, the Iraqi leader said.
The Islamic State was born out of al Qaeda’s Iraqi faction that battled U.S. and coalition forces during the bloody years of the U.S. war in the country. It broke with al-Zawahri and the Pakistani-based terrorist group in 2012 and formed the Islamic State in Iraq and the Levant, or the Islamic State in Iraq and Syria.
Al-Baghdadi remains in hiding within the group’s territory in Syria after reportedly fleeing its self-styled capital in Raqqa in March. Meanwhile, al-Zawahri reportedly remains in hiding along the Afghan-Pakistani border.
If such an alliance materializes, the Islamic State will not end with the liberation of Raqqa and Mosul, the group’s Iraqi stronghold, Mr. Allawi said.
“I can’t see ISIS disappearing into thin air,” Mr. Allawi said. “They will remain covertly in sleeping cells, spreading their venom all over the world.”
Those cells will not be limited to the group’s traditional redoubts in North Africa and the Middle East. As Islamic State factions and self-radicalized “lone wolves” in Western Europe and the U.S. have captured headlines with violent, high-profile attacks, the terrorist group has expanded its territory.
While al Qaeda has planted operatives inside the U.S. to plan, coordinate and launch attacks, those sleeper cells maintained ties to the group’s chain of command that U.S. and allied intelligence agencies could exploit.
The lack of such linkages, especially by lone-wolf attackers and returning fighters from Islamic State wars in Iraq and Syria, the potential cabal of terrorists threatening the West is surging.
“A lot of what comes out of ISIS is just, ‘Go where you can and kill who you can,’” Gen. Nagata said. “There’s an inherent danger to this, because their use of foreign fighters is more unpredictable.
“Even though they acted to save their skin by fleeing Iraq and Syria, there’s still a latent desire to wreak havoc. And they’ll find an outlet for that,” he said.
The Islamic State’s command structure also has allowed the group to take advantage of nontraditional networks tied to illicit trafficking and international organized crime groups, to move men, materiel and their virulent message into areas as far as Southeast Asia and South America.
U.S. Southern Command chief Adm. Kurt Tidd said his command was working with nations in the region to identify and shut down a growing number of suspected Islamic State terrorist cells.
“Right now, what we’re trying to do is identify the individuals themselves so that the countries can begin to try to pay attention to them and see what else they might be up to,” said Adm. Tidd, declining to specify the nations in Central and South America.
Drug smuggling routes through western and northern Africa, which South American drug cartels use to move narcotics across Europe’s southern borders, are controlled by the al Qaeda-affiliated Boko Haram and al Qaeda in the Islamic Magreb, the group’s West African cell.
While Iranian-backed terrorist groups such as Hezbollah have regularly maintained a fundraising presence in the region, the Islamic State is looking to establish an operational presence, Adm. Tidd said.
“We know that there was some [Islamic State] fundraisers that supported some of the foreign fighters that traveled over but what’s of concern now are individuals who may in fact be radicalized to the point of conducting attacks. That’s the danger,” Adm. Tidd told reporters at the Pentagon.
While the threat posed by returning Islamic State fighters is global, the responsibility for containing that threat is not, Gen. Nagata said.
“We’ve had to adapt our thinking about the fact, unfortunately, that the very welcome defeat of ISIS’ armylike capabilities in Iraq and Syria will not bring an end to the global terrorist attack threat that ISIS poses, including by the utilization of foreign fighters. Particularly if they return to their country, we’re relying on their judicial system,” the three-star general said.
The U.S. and its allies are doing their best, “but you know, if you want to hide, you can hide. If you want not to be counted, you can not be counted,” he said.