Anti-radicalisation campaigns have failed to prevent young and disaffected from turning to Isis in country with strong secular tradition

Months after the deadly Islamic State and al-Qaida-inspired attacks on the satirical magazine Charlie Hebdo, which left 17 people dead in Paris in January, France has fallen victim to another jihadi onslaught of even more horrifying proportions.

On Saturday, the French president, François Hollande, pointed the finger of blame squarely at Isis and labelled its attacks an ‘act of war’ – plotted and organised abroad, but executed, brutally, at home. In turn, came a claim of responsibility from Isis vowing France would “continue to smell the odour of death” as long as it continued its policies in the Middle East.

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The gunmen and suicide bombers have not yet been publicly identified, but Hollande admitted they had had help from inside France. If some or all turn out to be French citizens, it is likely to spotlight the government’s struggles to tackle radicalisation among its Muslim minority.

According to most estimates, France has lost more people to militant Islam than any other country in Europe: a report by the French senate in April concluded that at least 1,430 of the 3,000-plus known European jihadis who had then travelled to Syria and Iraq to fight for Isis were French.

The AFP news agency reported earlier this year that French intelligence services were monitoring another 1,570 people who authorities believed had some kind of connection to Syrian networks, while up to 7,000 more were considered at riskof heading down the same path.

Speaking on Friday night, Hollande said: “We know where these attacks come from,” without naming any individual group. “There are indeed good reasons to be afraid.”

More than 150 French radicals are serving prison sentences in France. But more alarming for the country’s hard-pressed security services is the fact that at least 200 French jihadis who have spent time in territory held by Isis are known to have since returned to the country.

The four-man group responsible for the attacks on Charlie Hebdo’s offices and a kosher supermarket in central Paris had connections to Isis through Amedy Coulibaly, who allegedly masterminded the assaults and claimed to be fighting for Islamic State; another of the attackers is known to have attended an al-Qaida training camp in Yemen.

Earlier this year, a report by the King’s College’s International Centre for the Study of Radicalisation and Political Violence found that only Saudi Arabia, Tunisia, Russia and Jordan had more of their own fighting with Isis than France; at that time there were more than twice as many French radicals as German and British fighters.

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Despite a number of anti-radicalisation campaigns by the French authorities, the government has seemingly been unable to prevent considerable numbers of the country’s 4.7 million-strong Muslim community – about 7.5% of the population – from veering towards violent radicalism and jihad.

The resentment of disaffected young men and women from a disadvantaged community frequently discriminated against in education, employment and housing has been further fuelled by largely symbolic measures they feel have been taken against Islam under France’s strong secular tradition, such as the 2010 ban on wearing full-face veils in public.

The first waves of Islamic militancy in France were linked to the civil war in Algeria, its former colony. In 1994, Algerian militants hijacked an Air France plane with the possible aim of crashing it into Paris. A year later, bombs exploded on public transport in the French capital.

Later in the decade, a few hundred Frenchmen made their way to training camps in Afghanistan, some run by al-Qaida. A network of activists linked to Osama bin Laden and other major figures in the new global jihad were active in France, preaching and recruiting. At least one Frenchman was killed during the final battles of the 2001 war in Afghanistan as the US-led offensive cleared the group and their Taliban hosts from the country.

Throughout the decade that followed, there were no bombings in France like those in Madrid or London, or even plots of the ambition seen elsewhere. Successive French government inquiries concluded urban riots in 2005, though portrayed as a Muslim ”rising” by some commentators overseas, had no religious component and, though French citizens continued to make their way to Afghanistan or Iraq to fight, and sometimes die there, they were still few in number.

The popularity of revivalist, if quietist and apolitical, groups such as the Tablighi Jamaat as well as a steady flow of young French Muslims to Egypt or Gulf States to study in religious schools was a serious concern, but major protests in 2006 following the publication of cartoons supposedly ridiculing Mohammed were entirely peaceful.

Polls showed young French second- or third-generation Muslims were increasingly integrated in terms of drinking alcohol or marriage with non-Muslims, even if they were also more likely to attend mosque or wear the veil. French officials in 2009 or 2010 were confident of their ability to handle any internal threat. This proved, however, over-confident.