Examining the threat posed by Dutch jihadists
22 August 2014 Last updated at 12:02 BST
Islamic State (IS) militants have been accused of a number of atrocities in Iraq and Syria - but it is not just people from the region who have been fighting for the group.
Radical young Muslims from various European countries have travelled abroad to join insurgent groups including IS.
More than a hundred Dutch citizens are believed to have joined the fighting in Iraq and Syria and others have been seen on the streets of Holland waving the black flag.
Anna Holligan reports from the Hague.