The symbolism and meaning of a jihadi attack is usually known only to the disturbed individuals who carry it out. Sept. 11 marked a battle three centuries earlier in the Ottoman crusades; London's July 7 bombings were meant to mar a G8 summit. Most others are opportunism: A chance, seized by a local citizen who believes in the overseas cause, to mete mortifying damage upon a target sensitive enough to get that cause in the headlines.
But driving a transport truck at speed through two kilometres of families marking Bastille Day on a beachside promenade leaves no room for ambiguity. It is the most unspeakably calculated meeting point of the foreign conflict and the local target. More so than hitting political satirists or Jewish markets or crowded airports: Nothing turns the Levantine territorial ambitions of a terrorist army a continent away into a local horror for the French than the sight of one of their fellow citizens delivering historic-scale agony on the national day.
France now faces two very serious problems. One is the deadly ambitions of the group that calls itself the Islamic State (or ISIS or ISIL), and the factors that turn a constant trickle of young Frenchmen into the agents of those ambitions, willing to murder their fellow citizens to change the direction of the Middle East.
The second problem – stopping the flow of local recruits – is profoundly difficult, as these recruits rarely have direct links to the Islamic State, and aren't easily identifiable in advance. The man who reportedly committed the truck attack in Nice, Mohamed Bouhlel, appears to fit the profile of most young Westerners who've joined the IS cause: A French citizen and long-term resident of the city, not religiously observant or from a religious family; a wife-beater with a history of petty crime.
That set of characteristics describes most of the men who've carried out grievous attacks in France and Belgium in the past two years, as well as those who've carried out North American attacks such as the Ottawa Parliament Hill shootings and the Orlando nightclub attack. It also describes an alarmingly large number of men who never go into terrorism. Intelligence and police agencies need to do more to try to apprehend such men before they attack, but the odds are long.
The first problem – the foreign movement that motivates and inspires these young men – sounds equally difficult. Yet it is the more important problem.
François Hollande, the French President, caught some criticism for responding to the attack on Friday morning by immediately ordering intensified attacks against IS in Syria and Iraq. After all, responding to domestic terrorism by dropping bombs on foreign countries has a long and unsavoury history.
But his instincts are right, because the motive factor behind this wave of attacks is not to be found in the West. Nor is the eventual solution.
We should not forget that this sequence of jihadi attacks, in Europe and North America, is not a perpetual or timeless thing. They had a beginning – in 2012. They resemble the earlier, infamous wave of attacks by Westerners loyal to al-Qaeda from 2001 to 2005. But it's important to remember that during the years between those waves – 2006 through 2012 – there were almost zero Islamic terrorist attacks in Europe or North America: with a few isolated exceptions, the flow of atrocities vanished during those years, because there was no foreign cause to motivate them.
And the Nice attack, like Paris or Brussels or Ottawa, was clearly a direct response to the ambitions and desires of this Syrian movement. In the weeks before Nice, IS's Internet channels, YouTube videos and magazines were full of messages calling on loyalists abroad to attack Western countries involved in the NATO campaign in general and France in particular; they've specifically suggested recently that ramming vehicles into crowds is a recommended tactic.
The purpose of these attacks is not to have meaning: It's to scare a country and its leaders enough that they remove themselves from the foreign territory claimed by the group the terrorist army sees as its own. Sept. 11 was meant to get the United States out of Saudi Arabia. July 7 was meant to get Britain out of Iraq and Afghanistan.
And the young men who sympathize with the group that calls itself Islamic State tell us they want to help it do what it wants: to take over a large "caliphate" without interference, and to divide the world into Islamic and non-Islamic territory.
That ambition is now being thwarted, as IS is driven out of the territory it once held. But as long as hope endures, the dream will live on. The tragic result is what IS's bulletins call "punishment" of nations supporting this military campaign. It makes this a tough moment: Military success overseas is provoking greater abominations at home.
That's because there are still plenty of violent young men susceptible to this overseas cause. Their string of attacks will only come to an end when their movement is so humiliated in its self-claimed nation that it ceases to be inspiring.