The threat of experienced militants returning to Europe from combat in North Africa and the Middle East is fueling debate about immigration and integration in Europe and strengthening xenophobic and nationalist sentiments. It is not a new phenomenon for Europeans to travel abroad to fight. Reports have circulated for months about the growing number of foreigners fighting alongside Islamists in places such as Libya and Syria. Most recently, Spanish newspaper El Mundo reported Aug. 5 that leaks by unspecified European intelligence services warned that terrorist organizations in Syria could be preparing international attacks, particularly in Europe.

As new intelligence emerges — whether the threats are legitimate or not — European authorities will intensify counterterrorism efforts and immigration controls in an effort to thwart possible attacks. But given the large and growing Muslim population in Europe and the ease of travel throughout the Continent, preventing all attacks will not be easy.

The El Mundo article identified the Syrian rebel group Jaish al-Muhajireen wal Ansar (Army of Emigrants and Helpers), formerly known as the Muhajireen Brigade, as a group that many foreigners join. Created in summer 2012 by foreign fighters and led by Chechens, the group has recruited foreign participants from all over the world and merged with two other Syrian rebel factions, the Khattab Brigade and the Army Muhammad, in February. According to the Chechen news agency Kavkaz Center, the group consists of roughly 1,000 fighters and has led assaults in the Syrian provinces of Aleppo, Latakia and Idlib, among others.

National Origins

In April of this year, EU Counterterrorism Coordinator Gilles de Kerchove estimated that some 500 European citizens were fighting in Syria, most of them from the United Kingdom, France and Ireland. A survey by the International Center for the Study of Radicalization at King’s College London found that up to 600 Europeans from 14 countries, including Austria, Spain, Sweden, the United Kingdom and Germany, have participated in the Syrian conflict since it began in early 2011, representing roughly 7 to 11 percent of the total number of foreign fighters in Syria. The study showed that the largest contingent of foreign militants — somewhere between 28 and 134 — came from the United Kingdom. (The number of foreign fighters could be higher considering that many likely cycled through the fighting arena and returned home in a very short time.)

Though no one knows the exact number of foreigners fighting in jihadist militant groups, reports occasionally surface about foreigners killed in action in Syria, Somalia, Libya and Yemen, among other countries. In March, for example, a Swedish man known by the nom de guerre Abu Kamal As Swedee and a Danish man known as Abdul Malik al-Dinmarki, both members of the Jaish al-Muhajireen wal Ansar, were reportedly killed in suicide bombings in Syria.

The Washington Institute for Near East Policy and Flashpoint Global Partners conducted a joint study this year that monitored extremist Internet sites and analyzed the national origins of 280 foreign fighters reported to have died fighting alongside rebels in Syria between July 2012 and May 2013. The study found that 60 of those killed came from Libya, 47 came from Tunisia and 44 came from Saudi Arabia. The death toll also included single fighters from countries such as Denmark, France, Uzbekistan, Ireland, Morocco, Turkey, the United Kingdom and the United States.

Jihadists Back Home

Muslim communities have existed in Europe for centuries, but guest-worker agreements and relaxed immigration policies in the 1960s brought waves of Muslim immigrants from Turkey into Germany, from Algeria into France and from Pakistan into the United Kingdom. EU cross-border travel restrictions are minimal, and some European authorities try hard not to disturb Muslim communities in hopes that inaction will safeguard Europe against attacks by radicalized Islamists. Compounding the problem is that returning jihadist fighters are more often than not European citizens and are usually not caught by standard immigration controls.

Hence, it has not been difficult for European Islamists to receive support from people and groups in the Middle East and North Africa largely undetected. Those connections can then be used to attempt to carry out terrorist attacks inside Europe. Below are some of the most recent attempted and successful attacks involving European jihadists:

• March 2013: A Belgian federal police counterterrorism force conducted a felony car stop that led to a shootout and the death of Hakim Benladghem, a French citizen of Algerian descent. Benladghem was known to have received training as a paratrooper with the French Foreign Legion. Police discovered a cache of weapons and explosives in his apartment and believed Benladghem intended to carry out an armed assault in Europe.
• August 2012: Spanish and French police foiled an al Qaeda plot by two Chechen men, Eldar Magomedov and Mohamed Ankari Adamov, and a Turk named Cengiz Yalcin. Their alleged plan was to drop improvised explosive devices from paragliders onto British and U.S. targets in Spain, France and elsewhere in Europe during the London Olympics. All three suspects were said to be al Qaeda operatives who had received training in Pakistan.
• July 2012: A Swedish national of Lebanese descent, Abu Abdurraham, plotted to blow up a U.S. passenger jet during the London Olympics. Abdurraham was believed to have converted to Islam in 2008 and was recruited for the operation in a terrorist training camp in Yemen.
• March 2012: A French-Algerian man named Mohammed Merah shot and killed a rabbi and three children outside a Jewish school in Toulouse, France. A week before the attack, Merah targeted a group of French paratroopers, killing four. He reportedly targeted army personnel because of his involvement with unknown militant groups in the war in Afghanistan.

In France and the United Kingdom, the threat posed by radical Islamists has become an important public issue, making both countries hesitant to supply weapons to Syrian rebels in spite of their earlier moves to end an embargo on such support. Both countries are also well aware that the large Muslim enclaves spreading throughout the Continent provide attractive havens for European jihadists who have received training in places such as Pakistan, Syria, Afghanistan, Yemen and North Africa. These communes provide effective environments for radicalization because of their relative isolation and the cultural and religious bonds they provide to largely disenfranchised immigrant populations.

Since the outbreak of instability in North Africa and extended fighting in Syria, the fear of attacks by nationals returning to Europe after fighting abroad has become widespread. It is a concern not only for France and the United Kingdom, both of which have sizable Muslim populations and have already seen terrorist attacks, but also for countries such as Denmark and Sweden, the latter of which is often portrayed as a positive example regarding the acceptance of immigrants.

Another Look at Immigration Policies

With border controls inside the European Union largely abolished, radicalized Islamists can easily threaten multiple countries, making collaboration among EU members more important. At the beginning of August, nine EU countries, including France, Belgium, Netherlands, Luxembourg, Germany, Poland, Italy, the United Kingdom and Sweden, called on the EU Parliament to support the establishment of a European database of airline passengers who enter and leave the European Union. While most EU countries already collect such data, it is not shared because the European Parliament is concerned about infringing upon privacy rights.

In order for EU members to better address the threat of jihadist attacks at home, security along the bloc’s borders will likely be tightened. This will affect not only potential terrorists but also other Muslim and European travelers. This could add pressure on countries such as the Balkan states — many of which are not part of the European Union, though they border EU territory and reportedly have seen extensive outflows of fighters to Syria — to increase their overall security efforts. Western European countries will probably provide aid in the form of money, personnel and hardware to those that need it.

In many European countries, immigrant populations are already under the spotlight because of rising unemployment. Right-wing parties, such as the National Front in France and the Freedom Party in the Netherlands, which are already gaining popularity in light of the European economic crisis, will fuel the fear that European jihadists will return from the battlefield to perpetrate attacks in Europe. This could lead to more criticism of European Muslim communities for their lack of integration. Rising unemployment, combined with the threat of returning jihadists, only increases the pressure on European governments to tighten immigration policy.

Europe’s Jihadist Outlook

Despite the large number of European Muslims who have received training overseas and fought in places such as Somalia, Libya and Syria, few have actually conducted attacks after returning to Europe. Still, in an era when jihadist ideologues are urging individual jihad in the West, these trained individuals do pose a very real threat.

One problem is that the manner in which fighters are recruited from Europe or elsewhere is inconsistent from one place to another and difficult to track. As a result, it is hard to determine who might carry out a terrorist attack, what type of attack it could be and where it might occur. This problem is compounded by many others, including the grassroots strategy propagated by al Qaeda and the difficulties of disrupting terrorist training that occurs abroad. Problems specific to Europe include the historical Muslim presence in the Continent and the relative ease of cross-border European travel. Authorities will continually be challenged in their efforts to thwart terrorist attacks, not only in Europe but anywhere there are vulnerable targets as well.