International Conflict and War ♦ Article 64 Va. J. Int’l L. 69 (2023)

Regulating the Foreign-Fighter Phenomenon

BENJAMIN R. FARLEY

The transnational mobilization of foreign fighters is a centuries-old phenomenon that threatens international security. The phenomenon challenges States’ sovereign monopoly on the use of force under international law. It augments the capabilities of parties benefiting from such mobilizations, often prolonging or intensifying armed conflict. It creates networks of trained and experienced private fighters who are unmoored from State direction and free to choose whether, when, and for what cause to fight. And it generates sometimes substantial pockets of aliens who are de facto exiled from their States of origin or habitual residence and pushed to participate in additional armed conflicts.

Despite these threats, today, the foreign-fighter phenomenon escapes specific international legal regulation. Consequently, in many circumstances, States of origin are—or behave as if they are—legally free to look the other way as their nationals depart for and participate in foreign armed conflicts. Likewise, in many circumstances, States of origin are—or behave as if they are—legally free to ignore their nationals’ onward travel to additional conflicts, where they may intensify ongoing situations of armed violence. Sometimes, States of origin dissuade or impede the repatriation of their nationals following their participation in armed conflicts, exacerbating international insecurity and shifting their security-related burdens onto other actors in the international system.

This Article argues that international peace, security, and stability can and should be improved by extending existing principles of international law to the foreign-fighter phenomenon and by clearly imposing obligations on States of origin to interrupt the typical foreign-fighter lifecycle. Such regulation should oblige States to, first, restrain the departure of their nationals or habitual residents for foreign conflict zones; second, readmit their nationals or habitual residents when they attempt to return; and, third, facilitate the repatriation of their nationals or habitual residents when they are detained in the context of a foreign armed conflict. These obligations would address the structural infirmities currently present in the international system that contribute to the prolongation and recurrence of the foreign-fighter phenomenon—and the non-ideological international insecurity it represents