September 28, 2016

TSG IntelBrief: The Paradox of Stemming Foreign Fighter Flows

• On September 27, FBI Director James Comey testified that the monthly average number of Americans trying to travel to join the Islamic State in Syria has dropped to one or less.

• The drop can be attributed to both effective proactive law enforcement, as well as the lessening attractiveness of the ‘caliphate’ as a destination.

• While there is concern over a potential ‘terrorist diaspora’ from Syria, the U.S. faces a threat from those who do not travel but will still attack at home.

• The Islamic State’s brand will outlast its territorial holdings, creating a persistent threat of directed and inspired attacks in the West for years.


The true expanse of the so-called Islamic State’s rise has been significant enough that what would normally be considered a categorical counterterrorism success—the sustained decrease in foreign fighter travel from the U.S. and Europe to Syria—is viewed with concern as to its near-term impact. As the Islamic State’s territorial holdings dwindle, the question remains as to whether the group’s supporters—no longer able to travel to a physical destination—will choose to attack where they are. This is a question that Western intelligence and law enforcement agencies are struggling to answer.

During his September 27 testimony, FBI Director James Comey warned again of a potential ‘terrorist diaspora,’ as persistent losses by the Islamic State may result in an unknown number of the thousands of foreign fighters who traveled to Syria and Iraq to head back home. This ‘bleed out’ was seen in much smaller, but still destabilizing, levels after the Afghan War in the 1980s, and the more recent war in Iraq. The number of foreign fighters that have traveled to the Islamic State dwarf those of previous conflicts. The U.S. has a relatively good handle on who has traveled to the group and who might try to return to the U.S., though Comey stressed the need for better biometrics to help with the challenge of preventing undetected returns by Islamic State fighters. The EU faces a much greater threat given the overall numbers of individuals that have traveled to Syria and the difficulties inherent in a common border system. The ongoing refugee crisis only exacerbates the challenge of detecting and disrupting extremist travel

Particularly in the U.S., the concern is as much about those who have not traveled to Syria but still have the desire to attack as it is about those seeking to return. While there is no way of knowing the answer, U.S. law enforcement and intelligence agencies must ask the question: how many Islamic State supporters in the U.S. that would have traveled to Syria if they had the ability to do so have now given up and are plotting to strike in the group’s name at home.

The Islamic State has tried to answer that question for its supporters. It has repeatedly called for those unable to travel to its territory to attack the group’s many enemies wherever and however possible. The final message given by Abu Muhammad al-Adnani—the recently deceased head of the Islamic State’s external operations branch—made note that the group’s reason to exist will not evaporate if the physical group disappears, and that its supporters should continue to fight. With every attack inside the U.S. by Islamic State supporters—whether small or large—the group can further incite supporters that may be disillusioned by recent losses and larger defeats soon to come. Cutting the flow of U.S. citizens trying to travel to Syria from an estimated 8 to 10 per month to nearly zero is a significant counterterrorism success, but it may also result in more individuals who intend to continue the fight on a different battlefield.


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