Six months after the Jan. 7 attack on the satirical weekly Charlie Hebdo, Paris remains a city on guard. Black-uniformed military police of the Republican Security Companies patrol tourist sites with submachine guns. Museums, concert halls and even bookstores funnel visitors through security checks under signs reading Vigipirate, the national state of alert that still hasn’t been lifted.

The French capital feels distinctly more security-conscious than even post-Sept. 11 Washington. And for good reason: The January attacks on Charlie Hebdo, in which 12 people died, and on a kosher supermarket, in which four hostages and a police officer died, were only part of a larger problem; France faces a continuing threat of terrorism inspired — perhaps even directed — by Islamic State.

On Friday, a man suspected of ties with Islamic extremists attacked a U.S.-owned gas factory near Lyon, leaving behind a severed head, a decapitated body and an Islamic flag.

And back in April, in an incident barely noticed outside Europe, police arrested a 24-year-old computer science student from Algeria after he accidentally shot himself in the leg and telephoned for an ambulance. The suspect, Sid Ahmed Ghlam, claimed that he had been attacked armed robbers, but when police searched his car and his apartment, they found what they described as “an arsenal” of automatic rifles and handguns, plus a list of potential targets. They quickly arrested two other men they said were co-conspirators.

The suspects’ plan, Interior Minister Bernard Cazeneuve said, had been to gun down parishioners at one or more suburban Catholic churches during Sunday Mass.

One element of the alleged plot stand out: It was aimed at ordinary churches — soft targets, not high-profile sites like such as government buildings and synagogues that get extra attention from the police. France has thousands of Catholic churches; it would be impossible for authorities to protect them all.

“The idea was to provoke a reaction — repression, civil strife — that would drive young French Muslims to join ISIS,” Jean-Pierre Filiu, a Middle East scholar at Paris’ Institute of Political Studies, told me, using an acronym for Islamic State. “It was part of a recruiting strategy. And it could have been a disaster.”

The French want President Obama to expand his focus beyond Iraq and intervene more directly against Islamic State in Syria.

Islamic State, in other words, isn’t merely urging supporters to launch random, symbolic attacks; it’s provoking chaos in Europe with the specific goal of attracting young Muslims.

Filiu said Islamic State prizes European recruits for an unexpected reason — not only because they can be trained for attacks in their home countries but because they can be used as ruthless enforcers of the group’s draconian rule in Syria, where they have no family ties that might lead to leniency.

“ISIS has a long-term terror strategy in Europe, and it’s working,” said Filiu, a former French diplomat who still advises government officials. “It’s a European 9/11.”

A former high-ranking French national security official told me Filiu’s assessment, while dramatic, isn’t an exaggeration.

“Europe’s governments are very worried,” he said. “We expect more attacks. The problem of ISIS is closer to us than it is to you.”

Fear has led to a predictable response: a massive increase in law enforcement and domestic surveillance efforts. In May, France’s Parliament passed a law expanding the government’s spying powers, including collection of metadata — the same practice Europeans denounced when Edward Snowden, the former National Security Agency contract worker, exposed its use by the United States. Meanwhile, conservative politicians, fighting for attention in the upcoming presidential campaign, have issued stark warnings of a growing Islamic threat.

But the real source of the problem, Filiu and other experts say, lies in Syria and Iraq, where Islamic State was born.

“The only real answer is to neutralize them at the source, in both Syria and Iraq, and that can only be done by Sunni Arabs,” Filiu said.

“The Iraqi army can’t do it. You need Sunni insurgents in both countries. Contrary to what Obama seems to think, we need them as much as they need us. They are the only defense line between Daesh [the Arabic acronym for Islamic State] and Europe.”

In short, the French want President Obama to expand his focus beyond Iraq and intervene more directly against Islamic State in Syria, including more aid to Syrian rebels who aren’t Islamic extremists.

That’s not a new policy. In 2013, French President Francois Hollande was the first foreign leader to endorse Obama’s plan to launch airstrikes against Syria in retaliation for the Damascus government’s use of chemical weapons against rebel neighborhoods. The French were exasperated when Obama changed his mind and canceled the strikes.

And now, because of Charlie Hebdo and the fear of further attacks, the French are quietly renewing their pleas for more American intervention. They don’t think they can do it alone, and they don’t think the European Union can agree on a joint effort.

Their message: The war in Syria isn’t just a Middle Eastern problem or a sectarian fight between Sunni and Shiite Muslims; it’s also a direct threat to U.S. allies in Europe — and that means the United States stays out at its own risk.