How can you stop young people from Western Europe setting off for Iraq and Syria to fight for the group calling itself the Islamic State?
It's a question that lots of people are trying to answer in many European countries, including France, where new laws have been just been passed.
The BBC’s Lucy Williamson reports on the challenge facing the French authorities.
- Lucy Williamson, correspondent for the BBC. She tweets @LucyWilliamson.
This segment aired on October 6, 2014.