Trends in the Return and Prosecution of ISIS Foreign Terrorist Fighters in the United States

Approximately 300 Americans are estimated to have traveled or attempted to join the Islamic State (ISIS) as part of the group’s campaign in Syria and Iraq between 2013 and 2019. These individuals joined more than 53,000 men, women, and minors from roughly 80 countries. Often referred to as foreign (terrorist) fighters (FTF), these are individuals from third countries who travel to join a terrorist group to support its activities. In the United States (U.S.) context, the FTF designation does not denote the act of fighting itself, but rather the support of a designated foreign terrorist organization (FTO). While many of these radicalized individuals traveled alone to the conflict zone, others brought their families or formed new ones in-theater. As ISIS’ selfdeclared caliphate collapsed, many were killed, some fled to other locations, and many were captured and held by Kurdish forces. Men and some teenage boys were primarily placed in prisons, while women and minors were often moved into detention camps.

Today, an estimated 10,000 male FTFs remain held in northeastern Syria including 2,000 men and boys from 60 countries outside Syria and Iraq (third country nationals, or TCNs). In addition, local camps hold close to 55,000 female FTF and FTF-affiliated family members, including roughly 10,000 TCN women and children. Some of these individuals have now been in detention for four years or more.

The indefinite detention of FTF and FTF-affiliated families in northeastern Syria is not a tenable solution. In addition to clear humanitarian concerns, there is a significant security risk that the facilities’ inhabitants provide a groundswell of recruits to the still active ISIS campaign in the region. A 2022 U.S. military report puts it bluntly, “These children in the camp are prime targets for ISIS radicalization. The international community must work together to remove these children from this environment by repatriating them to their countries or communities of origin while improving conditions in the camp.” In lockstep, U.S. diplomatic leaders have made repatriation a policy priority empowered by a general domestic partisan consensus that the repatriation of FTF and FTF-affiliated families from northeastern Syria should be done expediently.

Progress has been slow, while many Western nations were strongly resistant to bringing their detained citizens home, there is recent evidence for cautious optimism. Approximately 9,200 persons – including 2,700 TCNs and 6,500 Iraqis repatriated since 2019. This year, 13 countries have repatriated roughly 2,300 persons, including more than 350 TCNs. However, more work remains to be done.

As of July 15, 2023, 39 U.S. persons have been officially repatriated, including both adults and minors. At least 11 additional U.S. persons have returned on their own accord, ten of whom remained in the U.S. following their return. Furthermore, the U.S. has made the decision to bring several non-U.S. persons to the U.S. to stand trial.