Many of them were barely school age when their parents took them to the ISIS so-called "caliphate" in Iraq and Syria. Thousands of others were born there. The children are the most vulnerable of the ISIS captured followers — the remainders of the more than 40,000 foreign fighters and their families who came from 80 countries to help build the caliphate. Many are now detained in camps and prisons across eastern Syria, Iraq and Libya. “What have these kids done?” said Fabrizio Carboni, a Red Cross official, after witnessing the misery surrounding him on a recent visit to Al Hol camp in Syria. “Nothing.” Yet even when it comes to the children, the foreign governments whose citizens are marooned in the camps and prisons have struggled with what to do with them. ISIS, researchers say, employed children as scouts, spies, cooks and bomb-planters, and sometimes as fighters and suicide bombers. Propaganda videos showed young children beheading and shooting prisoners. Some have had years of ISIS indoctrination and, in the case of older boys, military training. “They’re victims of the situation because they went against their will,” said Peter Neumann, director of the International Center for the Study of Radicalization at King’s College London, “but that doesn’t mean that they’re not, in some cases at least, a risk.” If figuring out what to do with the children is that complicated, deciding what to do with the women and men is even more difficult. There are at least 13,000 foreign ISIS followers being held in Syria, including 12,000 women and children. That number does not include the estimated 31,000 Iraqi women and children detained there. Another 1,400 are detained in Iraq. But only a handful of countries — including Russia, Kosovo, Kazakhstan, Indonesia and France — have intervened to bring back some of their citizens. The debate is more pressing than ever. In overflowing camps in eastern Syria, the wives and children of ISIS militants who fled the last shreds of ISIS territory are dying of exposure, malnutrition and sickness. Children are too spent to speak. Women who have renounced the group live in dread of attacks from those who have not. The local militias running the camps say they cannot detain other countries’ citizens forever. Across the border in Iraq, government authorities are administering hasty justice to people accused of being ISIS members, sentencing hundreds to death in trials that often last no longer than five minutes. But most foreign governments are reluctant to take them back, leaving them international pariahs wanted by no one — not their home countries, not their jailers. “Who wants to be the politician who decides to repatriate Individual A who, two years down the road, blows himself up?” said Lorenzo Vidino, the director of the George Washington University Program on Extremism. The fact is, Mr. Vidino said, few extremists return to stage attacks in their home countries. But the exceptional cases — including the 2015 Paris attacks that killed 130 people and two of Tunisia’s deadliest terrorist attacks — have made the idea of repatriation politically toxic in many countries. At least one of the bombers who carried out the attack in Sri Lanka on Easter was a Sri Lankan who had trained with ISIS in Syria. Some countries, like Britain and Australia, have revoked the citizenships of their nationals suspected of joining ISIS abroad, effectively abandoning them and their children to indefinite detention without charge and potential statelessness. The New York Times