Foreign Fighters in History

The Islamic State group has mobilized tens of thousands of individuals from over 120 countries to fight in Iraq and Syria on behalf of the organization.1Although the scope and scale of the (mostly) Islamic State-inspired migration is unprecedented, the foreign fighter phenomenon has shaped military conflicts in recent history. As the Islamic State continues to shrink, and sheds fighters who joined the battle from abroad, lessons from previous conflicts featuring foreign fighters may be illustrative.

The “anti-Soviet Jihad” in Afghanistan in the 1980s was the first modern conflict to see high levels of foreign fighter participation. From that conflict, a global militant community established the funding networks, credibility, and battlefield proficiency operationalized in Bosnia and Chechnya a decade later.

These conflicts follow similar patterns: conflict-induced humanitarian crises eventually precipitate supranational struggles drawing worldwide volunteers. After September 11, 2001, subsequent foreign fighter mobilizations evolve in how fighters migrate, fight, and communicate, but maintain the basic commonalities that shaped the first conflicts. The personal networks built in Afghanistan strengthened in Bosnia and Chechnya and were critical to shaping the conflicts in Iraq and Syria. Returning fighters from previous conflicts moved on to found many of the terror networks that gave rise to current jihadi-salafi organizations such as al Qaeda and the Islamic State.

A new report by the Transnational Threats (TNT) Project entitled “Foreign Fighters in History” investigates case studies in foreign fighter history, and is available on the CSIS website here:

Thomas M. Sanderson