U.S. officials and analysts contend that the potential foreign fighter threat underscores the importance of close law enforcement ties with key European allies and existing U.S.-EU information-sharing arrangements, including those related to tracking terrorist financing and sharing airline passenger data. Some U.S. policymakers, including several Members of Congress, have expressed particular worries about European fighters in Syria and Iraq because of the U.S. Visa Waiver Program (VWP). Hearings in the 113 th and 114 th Congresses have addressed the potential foreign fighter threat, and several pieces of legislation have been introduced on the VWP. As noted previously, U.S. authorities judge that more than 20,000 foreign fighters have traveled to the Syria-Iraq region since the start of the conflict in Syria in 2011; of this figure, at least 3,400 are believed to be Westerners, including roughly 150 Americans. U.S. officials estimate that a handful of Americans have died fighting in the Syrian conflict since 2012. They also assert that military operations against the Islamic State group since August 2014 have killed thousands of fighters, including an unknown number of foreigners. Countering violent extremism . European Assessments and Responses33

		European Fighters: Increasing Numbers and Growing Concerns

Like the United States, European governments and the 28-member European Union (EU) have become increasingly alarmed by recent events in Syria and Iraq, especially the threat posed by the Islamic State organization to both regional stability and domestic security. Worries also exist about "lone wolf" attacks from those who may not have traveled abroad but have been inspired by Islamist extremist propaganda. Despite these efforts, finding ways to stem the flow of European fighters to the Syria-Iraq region and keep track of those who go and return remains challenging. European governments face budgetary and personnel resource constraints in seeking to identify and monitor a growing number of potential assailants. 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. These include the following:
enhancing information-sharing among member states and with EU bodies such as Europol (the EU agency that handles criminal intelligence) and Eurojust (the EU agency responsible for prosecutorial coordination in cross-border crimes); finalizing an EU-wide system for the collection of airline Passenger Name Record data to help counter terrorist threats and improve information exchanges among EU member states; strengthening external EU border controls by making full use of existing security tools provided in the framework that governs the Schengen area of free movement; preventing radicalization by detecting and removing Internet content that promotes terrorism or extremism, developing communication strategies to foster tolerance and counter terrorist ideologies, and addressing societal factors and situations in prisons that may contribute to radicalization; implementing strengthened EU rules to prevent money laundering and terrorist financing; increasing cooperation to curb the illicit trafficking of firearms given that the recent terrorist attacks in Paris and Copenhagen appear to have been carried out with military-grade weapons that are illegal in most European countries; and improving cooperation with international partners, especially in the Middle East, North Africa, the Sahel, and the Western Balkans. EU leaders have also agreed to "systematic" checks against relevant law enforcement databases of EU citizens flagged as possible terrorist suspects or returning fighters at the external borders. To combat the potential foreign fighter threat, Belgium has employed a mix of security measures and prevention efforts. The proposed new surveillance authorities could be particularly controversial given long-standing German concerns about privacy rights. The majority of these individuals came from Ceuta. Some U.S. policymakers, including several Members of Congress, have expressed particular worries about European fighters in Syria and Iraq because the U.S. Visa Waiver Program permits short-term visa-free travel for citizens of most European countries (see "Issues for Congress" for more information). Some proposed measures largely aimed to enhance the security of the VWP further (see H.R. U.S. officials point out that ESTA's introduction has greatly strengthened the VWP's security controls over the last few years and that the program's information-sharing provisions with participating countries help to enhance U.S. intelligence about known and suspected terrorists and other criminals.
The rising number of U.S. and European citizens traveling to fight with rebel and terrorist groups in Syria and Iraq has emerged as a growing concern for U.S. and European leaders, including Members of Congress. Several deadly terrorist attacks in Europe over the past year—including the killing of 17 people in Paris in January 2015—have heightened the perception that these individuals could pose a serious security threat. Increasingly, terrorist suspects in Europe appear to have spent time with groups fighting in the Middle East, especially with the Islamic State organization (also known as ISIL or ISIS). Others, like the gunman who murdered two individuals in Copenhagen in February 2015, seem to have been inspired by Islamist extremist propaganda.
U.S. intelligence suggests that more than 20,000 foreign fighters have traveled to the Syria-Iraq region, including at least 3,400 Westerners, since 2011. The vast majority of Western fighters are thought to be from Europe, although roughly 150 Americans have traveled or attempted to travel to Syria. U.S. authorities estimate that a handful of Americans have died in the conflict; they also assert that military operations against the Islamic State group since August 2014 have killed thousands of fighters, including an unknown number of foreigners.
European governments have employed a mix of security measures and prevention efforts to address the potential foreign fighter threat. These have included
increasing surveillance; prohibiting travel; countering terrorist recruitment and incitement to terrorism via the Internet and social media; and strengthening counter-radicalization programs.
Steps are also being taken by the 28-member European Union (EU) to better combat the possible threat given the bloc's largely open internal borders (which permit individuals to travel without passport checks among most European countries). EU leaders have emphasized the need to enhance information-sharing among national and EU authorities, strengthen external border controls, and improve existing counter-radicalization efforts, particularly online.
Nevertheless, European countries and the EU face a range of challenges in stemming the flow of fighters to Syria and Iraq and keeping track of those who go and return. Prosecuting such individuals 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. Due to ongoing resource constraints, even those governments with far-reaching legal authority to detain terrorist suspects have found it difficult to identify and monitor a growing number of potential assailants. Furthermore, implementation of several EU-wide measures under discussion could be slowed by national sovereignty concerns, long-standing law enforcement barriers to sharing sensitive information, and strong EU data privacy and protection rights.
U.S. officials and analysts contend that the potential foreign fighter threat underscores the importance of close law enforcement ties with key European allies and existing U.S.-EU information-sharing arrangements, including those related to tracking terrorist financing and sharing airline passenger data. Some U.S. policymakers, including several Members of Congress, have expressed particular worries about European fighters in Syria and Iraq because the U.S. Visa Waiver Program (VWP) permits short-term visa-free travel to the United States for citizens of most European countries. At the same time, many point out that the VWP's existing security controls require VWP travelers to provide advanced biographic information to U.S. authorities and may help limit travel by known violent extremists. 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 strengthen the security of the VWP further. In the 114th Congress, two proposals—H.R. 158 and S. 542—largely aim to enhance the VWP's security components to better guard against potential terrorist threats. For additional information, see CRS Report RS22030, U.S.-EU Cooperation Against Terrorism, by [author name scrubbed], and CRS Report RL32221, Visa Waiver Program, by [author name scrubbed].