The French police need two weapons.
One is called superslick, which makes concrete or asphalt too slippery to walk on. With a few police spraying it, the rioters cannot cross that line except on their hands and knees. With a little prior planning, they can arrest everyone in the riot. You box them in, then advance with special shoes that can walk over it, spraying in front of you. The rioters all fall down.
The other is “sticky foam”, large quantities of which can be sprayed at the rioters, utterly immobilizing them in goo that can only be removed with solvents. The US Marines used it with some success in Somalia.
In either case, a riot of 300 “youths” results in 300 arrests, which ends any value in rioting at all. They lose both their anonymity and their ability to escape.
But where is the victory in arresting all of them, only to grant them lifetime increased welfare checks and concessions, since the French obviously have mucked up severely in failing to provide assimilation for these rampant youths? There needs to be a volley of real lead bullets, followed by a volley of buses stopping just outside the border of France to disembark passengers.
Let’s not forget the new heat ray the DoD is introducing to Iraq.