ITV News Security Editor Rohit Kachroo examines what makes young westerners want to travel to a war zone in Syria.
Propaganda images of 17-year-old Samra Kesinovic surrounded by armed men and clutching an AK-47 helped turn her into a poster girl for the self-styled Islamic State.
But counter-terrorism agencies in Europe had hoped that she would eventually return home to become a symbol for all that’s wrong with IS.
She left her home in suburban Austria in April 2014 with Sabina Selimovic, her 15-year old friend.
Of course, dissent and disillusionment are not part of the fairy-tale sold to young westerners by IS.
So, Samra was forced to become a sex slave before being beaten to death, according to a former IS member who lived with the two girls in Raqqa.
Check-points and a chilling surveillance regime prevent some people from coming back.
The fear of what might happen is often the greatest obstruction to escape. Kadiza Sultana, one of three east London schoolgirls who fled for Syria last year, wanted to come back, but assessed the risk of being caught to be greater than the dangers of staying in Raqqa.
“Unfortunately it wasn’t possible to have her home before the risk caught up with her” said Tasnine Akunjee, the former lawyer for Kadiza’s family.
“There are examples of people who have gone out there, who have seen the lay of the land for what it is and discovered that it is far from the propaganda that’s espoused about it.”
For many fighters, life in the so-called caliphate is not what they thought it would be.
The brochures presenting a life in a macho nirvana, where video games and well-equipped gyms are easily accessible, is often exposed within a few days on the ground.
For young girls, a future under the spell of male domination is often underplayed in the online propaganda.
But several hundred of the 850 British citizens thoughts to have joined groups like IS are thought to have returned to the UK.
British citizens who have travelled abroad since 2012 to join terror groups have returned
According to one estimate, 400 British citizens who have travelled abroad to join terrorist groups such as IS since 2012, have since returned.
Security services fear that some returning IS fighters might launch attacks in Britain. It’s likely that a far greater number have fled for their own safety.
But they have left behind many foreign other recruits who calculated that a return journey to Britain to be more dangerous than their trip into Syria.