The prospect that thousands of the world's most fanatic jihadists could break out in the chaos caused by Turkey's invasion of northeastern Syria is causing widespread alarm.
The Kurdish administration guarding those suspected members of the Islamic State group is crumbling and their fate has never seemed more uncertain.
This is what we know about the detainees, whose fate has been a security and diplomatic hot potato for months:
How many?
Where?
Breakout risks
Transfers
IS relatives
Resurgence