On May 24, 2014, a man walked into the Jewish Museum in Brussels and opened fire, killing four people. This attack was more than just another incident of senseless gun violence. The alleged perpetrator, Mehdi Nemmouche, was a French national who had spent the previous year fighting in Syria; his attack was the first deadly spillover of the Syrian civil war into Europe. But Nemmouche is not alone—thousands of young Muslims from around the world have gone to fight in Syria and Iraq. The overwhelming majority of foreign fighters have come from the Arab world. But Europe’s 16 million and America’s 2 million Muslims can also feel the pull: The carnage in Syria, the refugee crisis, and the violence between religious communities in the Middle East have echoed throughout the West. Satellite television and social media bring images of sorrow and slaughter into the homes of Western Muslims every day.
U.S. and European security officials are paying attention. For many of them, Nemmouche’s violence is a harbinger of a wave of terrorism that could easily result in mass-casualty terrorist attacks in the West. FBI Director James Comey warned in May that “there’s going to be a diaspora out of Syria at some point and we are determined not to let lines be drawn from Syria today to a future 9/11.” These officials draw on their experience with the flow of foreign fighters that went to Afghanistan in the 1980s and their connection to the 9/11 attacks. They worry that Westerners might go to the region to fight dictators but will return as radicalized and battle-hardened foot soldiers of jihadist groups eager to bring the war to the West. Indeed, they note that the foreign fighter problem in Iraq and Syria is far bigger than in the past. Recent reports estimate that between 2,500 and 3,000 foreign fighters from Western countries have traveled to Syria and Iraq as of August 2014, including more than 100 Americans; France, Britain, Belgium, and Germany have the largest numbers of citizens in the fight. As the wars continue, the flow is likely to increase.
But while the threat of foreign fighters is real, it’s been exaggerated, and effective policy can further diminish it. Similar fears about foreign fighters have been raised before—especially after the 2003 U.S. invasion of Iraq—and those fears were largely not borne out. The battle against the Islamic State in Iraq and Syria and other Syrian jihadist groups is unlikely to be any different.
The vast majority of foreign fighters will never present a serious problem back home. Many of the most radical will die, blowing themselves up in suicide attacks or perishing in firefights with opposing forces. Many never return home, preferring to move on to the next jihad. Some of those who go to Syria and Iraq quickly become disillusioned, and even those who return with their illusions intact often have no plans for further violence, believing it is not a theater of jihad. Security services arrest or disrupt others, particularly if returnees group together to attempt large-scale attacks. Indeed, becoming a foreign fighter—particularly with today’s heavy use of social media—makes a terrorist far more likely to be identified by security services than if he had never left home. Intelligence officials are paid to worry, but they ignore their own remarkable record of success: They regularly detect jihadists and disrupt their plots, in locales ranging from Kosovo to Australia.
In contrast to al-Qaida in Pakistan, most jihadist groups in Iraq and Syria, including ISIS, have an agenda that is first and foremost local and regional: killing Alawites and Shia Muslims, toppling the Iraqi and Syrian governments, and so on. (The so-called Khorasan Group, which has strong links to the al-Qaida core, may be an exception.) Most Syrian jihadists have not prioritized the struggle against Europe and America. Even the U.S. bombing of ISIS forces does not necessarily change that calculus. ISIS beheaded American journalists but did not try to launch attacks outside the region, and its predecessor jihadist organization in Iraq fought U.S. forces for years after the 2003 invasion and did not attack the American homeland or carry out a significant attack in Europe.
The threat does require a response. U.S. and European governments need to identify opportunities to encourage potentially dangerous individuals to take more peaceful paths and to help determine which individuals deserve arrest, visa denial, preventive detention, or some other monitoring. Steps include increasing community engagement efforts to dissuade potential fighters from going to Syria or Iraq, working more with Turkey to disrupt transit routes, improving deradicalization programs to “turn” returning fighters into intelligence sources or make them less likely to engage in violence, and avoiding blanket prosecution efforts when fighters return. Most important, security services must be properly resourced to handle the potential danger. As the flow of foreign fighters increases, this may require increased funding. Taken together, these measures will reduce the likelihood that any one individual will either want to move or succeed in moving all the way down the path from concerned observer to foreign fighter to terrorist.
That said, terrorist attacks carried out by returnees from Syria or Iraq are almost inevitable. Terrorism has unfortunately become a feature of modern life. It cannot be eradicated, only controlled, and the fallout of the civil wars in Syria and Iraq will make that problem more difficult. The United States and Europe have dealt with this problem before and already have effective measures in place to greatly reduce the threat of terrorism from jihadist returnees. But the standard of success cannot be perfection. If it is, we are doomed to fail and, worse, doomed to overreact.
A longer version of this article appears in the November/December issue of Foreign Affairs.