CRS Insights
European Security, Islamist Terrorism, and Returning Fighters
Kristin Archick, Specialist in European Affairs (karchick@crs.loc.gov, 7-2668)
Paul Belkin, Analyst in European Affairs (pbelkin@crs.loc.gov, 7-0220)
March 16, 2015 (IN10209)
Terrorist Attacks in Europe and Mounting Security Concerns
European concerns about Islamist terrorism have been heightened considerably by recent attacks in
France and Denmark. In early January 2015, gunmen killed 17 people over several days in three
related incidents that targeted the Paris headquarters of French satirical magazine Charlie Hebdo,
police officers, and a kosher supermarket. The perpetrators of the attacks were French-born Muslims,
with possible ties to Al Qaeda in Yemen or the Islamic State terrorist organization. In mid-February
2015, a Danish-born citizen of Palestinian descent murdered two individuals—one at a Copenhagen
cafe that had been hosting a free speech debate, another at a synagogue—and wounded five police
officers.
These incidents—along with the May 2014 killing of four people at the Jewish Museum in Brussels,
Belgium, reportedly by a French Muslim who had spent a year with Islamist fighters in Syria—have
reinforced growing unease throughout Europe about the possible threats posed by European Muslims
fighting with extremist groups, especially in Syria and Iraq. Security services warn about the potential
danger such trained militants might pose if and when they return to Europe, and worry about those,
like the suspected Danish gunman, who may be inspired by Islamist extremist propaganda to commit
"lone wolf" attacks at home without ever traveling abroad.
Although it is difficult to assess the precise number of Muslims from Europe who have joined extremist
groups in Syria and Iraq, European officials believe that their ranks have increased significantly over
the past two years. Recent estimates from Europol, the European Union's (EU's) joint criminal
intelligence body, suggest that at least 3,000 and upward of 5,000 EU citizens have left to fight in
Syria, Iraq, or other conflict zones. A January 2015 study by the London-based International Centre for
the Study of Radicalisation indicates that up to 4,000 individuals from Western Europe have become
foreign fighters in Syria and Iraq. Key countries of origin reportedly include Belgium, Denmark, France,
Germany, the Netherlands, Spain, Sweden, and the United Kingdom. The conflict in Syria and Iraq has
also attracted fighters from the Balkans (especially Bosnia, Kosovo, and Albania) and Russia.
European Policy Responses
European governments have employed a range of measures, including increasing surveillance and
prohibiting travel, to combat the potential foreign fighter threat. Individuals suspected of planning
travel to Syria or Iraq—or recruiting others to do so—have been arrested in several countries (including
Belgium, France, Germany, the Netherlands, Spain, and the United Kingdom) on terrorism charges.
France, Germany, the Netherlands, and the United Kingdom have enforced rules that permit the
confiscation of passports or travel identification documents. Other European governments are
considering new legislation to permit prosecuting those who travel or attempt to travel abroad for
terrorist purposes, as required by U.N. Security Council Resolution 2178. European officials are also
seeking to more aggressively counter radicalization and extremist propaganda, especially via the
Internet and social media. Some have called on U.S. technology companies to assist these efforts by
preemptively removing terrorist content from their sites.
France, which is home to Europe's largest Muslim population (about 5-6 million) and the source of the
largest number of European fighters in Syria and Iraq (about 1,400), has been at the forefront of
European efforts to counter the threat posed by Islamist militants and returning fighters. In 2014, the
government took steps to strengthen counterterrorism policies already considered some of the most
stringent in Europe. These included imposing travel bans on individuals suspected of seeking terrorist

training abroad and blocking websites that encourage terrorism. After the Paris attacks, French
authorities announced additional significant measures, such as hiring 2,500 new law enforcement
officials and boosting counter-radicalization programs, especially in French prisons.
Nevertheless, stemming the flow of European fighters to Syria and Iraq and keeping track of those who
go and return remains challenging. Prosecuting individuals preemptively is difficult in many European
countries because most existing laws require a high level of proof that a suspect has actually engaged
in terrorism abroad or has returned to commit a terrorist act. Furthermore, as the attacks in France
demonstrate, even those governments with far-reaching legal authority to detain terrorist suspects
have been challenged to identify and monitor a growing number of potential assailants. Given
budgetary and personnel resource constraints, experts assert that it may be unrealistic to expect
governments to effectively monitor every individual identified as a possible security threat.
Analysts assert that more steps must also be taken at the EU level to better combat the potential
foreign fighter threat given the EU's largely open internal borders (which permit individuals to travel
without passport checks among most European countries). In February 2015, EU leaders reiterated the
need for enhancing information-sharing among national and EU authorities, strengthening external
border controls, and improving existing counter-radicalization efforts, particularly online. However,
implementation of some of these initiatives and other possible EU-wide measures—such as
harmonizing criminal laws against "jihadi travel" among the EU's 28 member states—could be impeded
by national sovereignty concerns, long-standing law enforcement barriers to sharing sensitive
information, and civil liberty protections.
Pressure has also increased to approve an EU-wide system for the collection of airline Passenger Name
Record (PNR) data, which has been stalled in the European Parliament—a key EU institution—since
2013 because of data privacy and protection concerns. In mid-February 2015, the European Parliament
passed a resolution on anti-terrorism measures and pledged to work toward finalizing the EU-wide PNR
proposal by the end of the year. A revised PNR proposal was presented in the Parliament on February
26, but observers caution that some Parliamentarians still worry that it could infringe too much on data
privacy rights and may seek to link approval to progress on broader EU data protection reforms.
U.S. Interests
U.S. officials, including some Members of Congress, have expressed particular worries about the
growing number of Europeans fighting with Islamist extremist groups abroad because the U.S. Visa
Waiver Program (VWP, see CRS Report RL32221, Visa Waiver Program) allows short-term, visa-free
travel between the United States and most European countries. In the 113th Congress, several pieces
of legislation were introduced on the VWP, ranging from proposals to limit or suspend the program to
those that sought to enhance the VWP's security controls further (one proposal, H.R. 158, has been
reintroduced in the 114th Congress). U.S. policymakers contend that the foreign fighter phenomenon
underscores the importance of maintaining close U.S.-EU counterterrorism cooperation (see CRS Report
RS22030, U.S.-EU Cooperation Against Terrorism) and existing U.S.-EU information-sharing
agreements, despite increased scrutiny from the EU following the unauthorized disclosures of classified
U.S. surveillance activities since June 2013. U.S. officials have also encouraged the EU to establish its
own PNR system and to make greater use of existing EU-wide databases and information-sharing tools.