A US general warned Saturday that the Middle East faces the looming threat of an ISIS group "army in detention", after visiting prisons and camps in northeastern Syria holding suspected extremists and their relatives. General Michael Kurilla, head of the US military's Central Command, visited several detention facilities this week, including Ghwayran prison in the city of Hasakeh, where hundreds were killed after extremists stormed it early last year, a CENTCOM statement said. "In visiting the detention facility, I saw the looming threat posed by this group of detained ISIS fighters," Kurilla said in the statement. "Between those detained in Syria and Iraq it is a veritable 'ISIS army in detention'. If freed, this group would pose a great threat regionally and beyond," he added. The Kurdish-led Syrian Democratic Forces (SDF), supported by a US-led coalition, spearheaded the fight against ISIS in Syria, driving the group from its last redoubt in the country in 2019. Tens of thousands of people, including relatives of alleged extremists, have been detained in the years since in camps run by the Kurdish authorities, including the notorious Al-Hol camp, where around 10,000 foreigners are held. Kurdish authorities have repeatedly called on countries to repatriate their citizens, but foreign governments have allowed only a trickle to return home, fearing security threats and domestic political backlash. SDF commanders and administrators at Ghwayran prison described the detainees as "unrepentant, subject to further radicalization to violence, and a ticking time bomb", CENTCOM said. Kurilla also visited the Kurdish-run camps of Roj and Al-Hol, where relatives of suspected extremists are held. Children in Al-Hol "are in daily danger of indoctrination to violence", CENTCOM said, adding that teenagers with foreign parents "expressed a desire to return to their country of origin". Kurilla urged the "repatriation, rehabilitation and reintegration of the camp residents back into their countries and communities of origin", calling Al-Hol a "flashpoint of human suffering". The extremists were ousted from Iraqi territory in 2017 but retain sleeper cells in desert and mountain hideouts in both Syria and neighboring Iraq. Suspected ISIS militants killed three truffle hunters and kidnapped at least 26 others in northern Syria on Saturday, a war monitor said. The fight against the extremists "is a fight for security and stability of not only Syria and Iraq, but the entire region", Kurilla said. "We absolutely cannot allow a resurgence of ISIS."