Last week’s appalling attack in Nice, which killed 85 civilians, offers another horrifying reminder of the threat from Islamist violence.
It is the latest terrorist assault on France that has already witnessed the killing of Jewish students and teachers in Toulouse, the Charlie Hebdo shootings and last November’s massacre in Paris.
France is an attractive target for radicalised Muslims because it is a bastion of the values they despise most.
The French emphasis on secularism has outraged jihadists with the ban on the Islamic face veil causing particular anger.
The country is also an epicentre of free speech where criticism of religion, including satire, is (rightly) welcomed.
For most of us, this land of liberty is a resplendent symbol of civilisation and freedom. For the jihadists, it is a hated symbol of decadence.
Inside the banlieues, where a modern generation of young Muslims often feels alienated from their host country, criminality and radicalisation abound, especially when militant Salafism is being preached in prisons and on the internet.
It is no surprise that the country has sent as many as 1,800 recruits to fight with IS in Syria.
In addition, France has taken an assertive stance against overseas Islamist extremism, sending troops to both Mali, Afghanistan and Syria.
Thus the great Republic is seen as a barrier to the warped fantasies of a Caliphate.
The jihadist threat requires concerted action. The global campaign against IS should be stepped up with increasing intensity.
Intelligence must be co-ordinated to ensure that those who are on the radar of the authorities are intercepted and their plots foiled. Above all, France should learn some valuable lessons from their Israeli counterparts.
For decades, the Jewish state has had to face a protracted threat from terrorism.
Israel has used human intelligence to penetrate Muslim communities, using informers where necessary.
In addition, her major public events have been properly protected with roads blocked off and city centres given multiple layers of security.
Israelis cannot afford to be complacent about terrorism, and neither can Europeans.
In the long run, enhanced counter terrorism will be more effective than a hashtag.