The country has the highest number of citizens who joined Daesh in Syria and Iraq among EU members nations.
One of the big questions hanging over Saturday's meeting of Turkish, Russian, German and French leaders in Istanbul is what to do about foreign fighters who travelled to Syria and Iraq to join Daesh.
More French nationals joined the terror group than any other European nationality.
The French government has long been aware it has a problem with hardliners in its prisons — the Charlie Hebdo attackers, for example, came under the influence of an extremist mentor while jailed.
There are about 1,500 prisoners in France the government considers radicalised. Of those, about 350 were jailed in France after returning home from fighting with Daesh in Iraq and Syria.
The country now needs to find a way to reintegrate hundreds of potentially dangerous inmates who spent years in war zones. One strategy adopted by the French government is to persuade convicted terrorists to abandon extremism.
French authorities now say they've learned from previous mistakes, but are not certain if they'll ever be able to reintegrate returned fighters back into French society.
TRT World's Elena Casas reports from Paris.