France's government has backtracked on a policy that allowed children to leave the country without their parents' permission.
The move comes after years of complaints from families of radicalised teenagers who left to join extremist groups.
The new rules requiring parental permission go into effect on Sunday, five years after the government lifted the restriction with little fanfare, citing a need to streamline bureaucracy.
At the time, the war in Syria was picking up and France became Europe's largest source of recruits in the war zone, notably for Islamic State.
Families said they were blindsided when their teenage sons and daughters were allowed to pass through border control with no questions asked and even to leave Europe's passport-free zone for Turkey.