The death toll in yesterday’s terrorist attack in Nice has risen to 84, including two Americans — a father and son on vacation in France. The death toll puts it among the worst terror attacks in the last several years, a rising percentage of which are taking place in France. Unlike in past attacks, though, this terrorist does not appear to have been previously suspected of terrorist sympathies, although he did have a record of petty crimes, according to CBS:

CBS News has confirmed the driver is 31-year-old Mohamed Lahouaiej Bouhlel, a French citizen born in Tunisia, according to law enforcement sources. He was known to police for petty crimes, reports CBS News correspondent Elizabeth Palmer. Police shot and killed the attacker.

At least 84 people were killed, including at least 10 children. Dozens of others are hurt. …

Authorities found a handgun, assault rifle and fake hand grenades in the truck. An investigation is ongoing to determine whether this was a lone wolf attack.

ISIS-linked terrorists staged two waves of attacks in France in 2015, which killed 147 people. Back then French President Francois Hollande declared that France was at war. After Thursday’s attack, he said, “France weeps. But France is strong. And will always be stronger than the fanatics that strike at her.”

The terror attacks in Paris killed more people, but it also took much more coordination and resources. Bouhlel appears to have acted alone in the attack phase, at least, and didn’t use any other weapon except a rather common truck. This raises questions about whether future terrorist plots will shift downward to lower-tech, single-attacker scenarios that would be much more difficult to predict and prevent. That’s especially true in this case, if it does turn out that Bouhlel gave no indications of radicalization and stayed off the radar screen of counter-terror agencies.

These attacks seem to be coming with some regularity in France. CNN asks why France has become a high-priority target, but the answer appears to be simply that it presents far more opportunities for home-grown radicalization. Combine disaffection from mainstream French society and the isolation of the banlieus, and you get a recipe for unstoppable terrorism:

“You have a very large disaffected North African community. They are French citizens now … but they’ve been excluded from French society,” Robert Baer, a former CIA operative, told CNN’s Don Lemon Thursday night.

“I went to school in France … I worked there and they are really totally excluded,” Baer added.

“And it keeps getting worse since the attacks in Paris because (police) are using profiling and they are stopping people who look like Arabs on trains and buses, checking their IDs, which we don’t even do in this country. The French have been very aggressive … radicalization of people of North African origin is actually picking up rather than lessening.” …

Tom Fuentes, a former FBI assistant director who served on the executive board of Interpol, said homegrown terrorism is a major concern in Europe.

“We have third-generation immigrants that came there from Morocco, Algeria, Libya, Tunisia … and even when their children are born in France and their children’s children are born in France, they don’t consider themselves French,” he said.

“These immigrant populations stay in confined neighborhoods and only assimilate with each other and aren’t accepted into the general population.”

This threat has been well-known for a decade or more. It has only become especially acute of late because of the emergence of ISIS. Prior to that, the banlieus were festering centers of recruitment and plotting, but the rise of a so-called “caliphate” has provided an impetus for direct action, well-planned or not. The refusal to press for assimilation, as well as unfettered immigration from north Africa over several decades, has made this problem both chronic and massive. It might take decades to unwind, but in the short run the first solution is to destroy ISIS and remove some of the support and inspiration it provides.