Marcon takes advantage of emotional reaction

An apparent Islamist fanatic, already under suspicion and monitored by the state, murdered a teacher in a French high school. Macron took advantage of the emotional reaction to the murder by calling for a "ruthless" response.

I can't see how "ruthlessness", as such, would help prevent future terrorist murders. It sounds like a way to stir up hatred against Muslims.

A more strict system of surveillance, applied by courts to people whose actions have justified it, might help.