In hundreds of French "no-go" zones  -- neighborhoods where neither tourists nor cops dare enter -- poor and alienated Muslims have intimidated the government into largely ceding authority over them, prompting fears that the kind of jihad that gave rise to last week's attack in Paris is festering unchecked.

“Most of the time, these are quiet places with nothing going on. But they’re apt to flare up.”

- Daniel Pipes, Middle East Forum

In some ways, these 751 areas designated by the French government -- officially called zones urbaines sensibles (sensitive urban zones), or ZUS, for short, but referred to as “no-go” zones by some observers -- resemble poor sections of America’s cities where gangs rule, crime and drugs are rampant and police only enter with significant backup. But in the wake of last week’s massacre at Charlie Hebdo and the fact that hundreds of radicalized Muslims who went to train or fight in Syria and Iraq could return, some experts fear the next terror attack will be launched from inside one of France's no-go zones.

“These ‘no-go’ zones are essentially breeding grounds for radicalism, and it’s a very big problem,” Soeren Kern, a senior fellow at the Gatestone Institute, told FoxNews.com. “These are areas where essentially the French government has lost control.”

Created in 1996, the zones are sprinkled throughout cities and suburbs in rundown neighborhoods France sought to revitalize with tax breaks for businesses. Most of the zones are blocks of neighborhoods, with the average ZUS containing about 6,000 residents. An estimated 5 million people live the zones, and most of the residents are part of France's 10 percent Muslim population. In some zones, Islamic law actually supersedes the French legal system on civil matters such as property disputes, adultery and divorce.

“Most of the time, these are quiet places with nothing going on,” said Daniel Pipes, the president of the Middle East Forum, a conservative think tank. “But they’re apt to flare up.”

Examples of flare-ups within the last decade include the infamous 2005 riots, when the accidental deaths of two teenagers in an impoverished Paris suburb during a police sweep touched off a national wave of unrest. For the next three weeks, violent clashes between immigrant youths and police took place in nearly 300 towns and suburbs, resulting in the torching of schools, community centers and thousands of cars, as well as nearly 3,000 arrests and an estimated 200 million euros in damage. Two years later, when two minority teenagers were killed after their motorscooter collided with a police car in a blue-collar town on Paris’ northern edge, rioting and arson ensued for several days. That time, however, the rioters -- joined by what a police union official called “urban guerrillas” -- fought police officers with shotguns and gasoline bombs, injuring dozens.

Part of the problem, say experts, has been an inability of France to assimilate its Muslim population. Unlike America, where each passing generation seems to become more integrated into the national identity, the opposite is true in France, experts say, with the relationship between the overwhelmingly white, Roman Catholic majority and dark-skinned, Muslim immigrant community becoming more estranged in the past decade.

In 2004, the government passed a controversial law prohibiting the wearing of religious apparel in France’s public schools, including Islamic head scarves. The move triggered demonstrations by Muslims around the world. Seven years later, France formally banned full-face veils in public places, ostensibly as a security measure but widely seen as an affront to Islamic custom and a way to make Muslim women feel unwelcome in French society.

As the divide grows, many second- and third-generation Muslim youths, seeking an identity and a sense of belonging, are becoming more religious than their parents and grandparents.

“These kids … have no relationship to Morocco or Algeria at all, but they’re not integrated into French society at all,” Kern said. “In a way, they’re stateless. They get drawn to radical Islam as a way to give them meaning in their life.”

Meanwhile, immigrants, particularly those from northern Africa, have difficulty landing good jobs or climbing in French society. A Newsweek correspondent estimated in August that 40 percent of young French Muslims from immigrant backgrounds are unemployed, and a 2010 Stanford University study found that a Christian of African heritage was two and a half times more likely to get called for a job interview in France than an equally qualified Muslim with the same ethnic background.

With much of the country’s Muslim population living in the downtrodden ZUS, they’re vulnerable to jihadist recruitment. A poll conducted last summer by Russian news agency Rossiya Segodnya found that 15 percent of French citizens had a positive opinion of the Islamic State terror group, also known as ISIS, or ISIL, and last month, French Interior Minister Bernard Cazeneuve revealed that twice as many French nationals in 2014 had joined or were planning to join ISIS than in 2013.

“You see these disenfranchised people, and it’s a very good recruitment pool,” said Scott Stewart, the vice president of tactical analysis of Stratfor Global Intelligence. “(Jihadists) are looking for angry, underemployed guys. It’s a good target audience for them.”

Among that audience were the three men linked to last week’s rampage at Charlie Hebdo and the subsequent manhunt that ultimately claimed 17 victims. The brothers behind the attack, Said and Cherif Kouachi, were French citizens of Algerian descent who were known to authorities for years. Cherif, the 32-year-old younger brother, was part of a cell known as the 19th arrondissement network, a group located in northeast Paris that sent European Muslims to fight in Iraq after the U.S.-led 2003 invasion. Along with several others, he was convicted in 2008 on terror charges, but he did not serve any time after conviction because part of his sentence was suspended and he was credited for time served in his pre-trial detention.

It’s also emerged that Said Kouachi, 34, had traveled to Yemen in 2011 and had direct contact with an Al Qaeda training camp. And Amedy Coulibaly, 32, a French citizen of Senegalese descent who claimed to be a compatriot of the brothers and was gunned down Friday at a Kosher grocery store in east Paris after killing four hostages, had declared allegiance to ISIS in a video that emerged on Sunday.

But while authorities piece together the events and causes behind last week’s events, debate is underway on how French authorities should try to assert more oversight and better relations with those in the ZUS.

Kern wants to see European governments crack down on welfare benefits that he believes entice immigrants, particularly for those with polygamous families. Pipes believes the French government should impose more restrictive immigration policies while demanding newcomers embrace western culture and its freedoms of expression.

Michele Lamont, however, a Harvard professor of sociology of African and African-American studies who is an expert on racism in France, fears that a hard-line response would only inflame tensions further. She believes the majority of Muslims want to be integrated with the rest of the French society, and the aftermath of the Charlie Hebdo attacks will be a critical time during which the nation’s Muslim population will either be drawn closer to the rest of the country or face further estrangement.

“It pushes all Muslims to make choices about where they stand,” she said.