"In the two years since the self-declared Islamic State lost its last physical stronghold in Raqqa, Syria, thousands of ISIS foreign fighters, along with their wives and children, have remained in limbo, mostly in Iraqi custody or in Kurdish detention camps in northeastern Syria. The question now is what to do with them — an issue that gained urgency following a United Nations Security Council briefing last month on a resurgence of ISIS in Syria. Roughly 40,000 traveled to the self-declared Islamic State from 81 countries. Some fought in Iraq and Syria for ISIS, while others, including some women and their children, were victims of violence. Whether they came willingly or not, those who remain — some 64,000 from 57 countries, mostly women and children — live amid dire conditions that human rights groups have described as breeding grounds for future radicalization. What should happen next to the fighters is relatively clear, according to international law experts. “All terrorist crimes need to be prosecuted,” said Naureen Fink, executive director of The Soufan Center, a global security research institute, echoing a sentiment expressed by all 17 extremism and counterterrorism experts with whom FRONTLINE spoke for this story. Who should be responsible for holding those trials is not so straightforward. There is no international tribunal with a mandate to prosecute ISIS-related crimes, and the International Criminal Court does not have jurisdiction in Iraq or Syria. Iraq has tried more than 20,000 cases of ISIS-related crimes. But with a judicial system internationally criticized for due process and human rights violations, Iraq poses a dilemma for countries with conflicting human rights standards. And while they’re considered an ally by the U.S. in fighting ISIS, the Kurdish forces running the camps in northeastern Syria are not recognized as a government with the authority to hold trials."