Under the protection of the Syrian Kurdish forces are about 15 thousand jihadists.
US officials in charge of counterterrorism are concerned that Islamic state militants captured while fighting in Syria could return to terrorist activities.
Of particular concern are about 2 thousand foreign fighters who are held in makeshift prisons of the Syrian democratic forces, supported by the United States because their home countries refuse to take them back.
For months, the US State Department and the Pentagon have urged States, especially those who helped the coalition defeat ISIS, to repatriate and prosecute their citizens who joined the self-proclaimed Caliphate.
But these requests have not met with a noticeable response: some countries, especially European ones, have expressed concern that their legal systems will not successfully prosecute jihadists whose alleged crimes will be extremely difficult to prove.
Turkey’s incursion into northeastern Syria last month forced the US’s main partner in Syria – the mostly Kurdish Syrian democratic forces-to withdraw guards from prisons to fight Turkish-backed forces.
Kurdish representatives said that they were forced to evacuate part of the prison and move the prisoners of the jihadists in temporary places of detention.
At the same time, about a hundred former ISIS fighters escaped. There are fears that if Turkish troops move deeper into Syrian territory, eventually there will be no one left to guard the remaining ISIS prisoners.
The United States believes that the Syrian democratic forces are holding in custody about 15 thousand ISIS prisoners.