A horrified France was grappling with a new reality on Thursday in which hundreds of its citizens are openly joining jihadist groups and directly calling for attacks on their homeland.
A new video from the Islamic State group released on jihadist forums and Twitter on Wednesday showed three Kalashnikov-wielding Frenchmen burning their passports and calling on Muslims to join them or stage attacks in France.
The new video explicitly calls for retaliation against France for launching air strikes against the Islamic State group, which has seized large parts of Syria and Iraq.
The violence continued on the ground with IS claiming a rare suicide car bombing in the usually secure capital of Iraq's autonomous Kurdish region that killed four people a day earlier.
Also in Iraq, Turkish Prime Minister Ahmet Davutoglu and his Iraqi counterpart Haidar al-Abadi held talks on security cooperation, pointing towards a possible easing in the long-strained ties between their countries.
The latest IS propaganda film follows the appearance of a grisly IS execution video at the weekend that featured at least one French citizen -- 22-year-old Maxime Hauchard.
Defence Minister Jean-Yves Le Drian announced on Wednesday that France would step up its campaign against the jihadists, sending six Mirage fighter jets to Jordan in December.
France currently has nine Rafale jets based in the more distant United Arab Emirates as part of a US-led international campaign to provide air support to Iraqi and Kurdish forces fighting the group.
Its most recent strikes, Le Drian said, targeted trenches used by IS fighters around the northern Iraqi city of Kirkuk on Tuesday.
- 'We know the dangers' -
But France is increasingly looking inwards as it reels from the news that over 1,000 people from a wide range of backgrounds have left to join the jihadists in Iraq and Syria, with 375 currently there.
French prosecutors on Thursday opened an investigation into the latest video and intelligence sources told AFP they were working to identify the three Frenchmen, including with the use of facial recognition software.
Prime Minister Manuel Valls said Wednesday that "close to 50" French citizens or residents have been killed in the conflict zone.
Figures published in Le Monde newspaper this week found almost a quarter of those who left to join the jihadists are converts to Islam, with many coming from everyday French backgrounds.
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One study from the Centre for Prevention Against Islamic Sectarianism recently found that 80 percent of parents reporting concerns about their child's radicalisation described themselves as atheist.
- Non-Muslim origins -
Hauchard, for instance, came from a small village in Normandy where he is remembered as a polite and amiable neighbour prior to adopting radical Islam in his teens.
Prosecutors also identified a second suspected French citizen in the video -- Mickael Dos Santos from the riverside town of Champigny-sur-Marne near Paris, who is known to have joined the Islamic State group.
But experts have since suggested the prosecutors may have been mistaken, arguing that the man in the video is a native Arabic speaker rather than a convert from France. Dos Santos is thought to be of Portuguese origin.
United Nations chief Ban Ki-moon said Wednesday that violent extremism had to be tackled "at the grassroots level".
"We must continue to think more deeply into the fundamental conditions that allow extremism to thrive. Looking at these challenges solely through a military lens has shown its limits," he told a special Security Council meeting on counter-terrorism.
France is far from alone in dealing with the problem.
A Dutch 19-year-old who allegedly travelled to Syria to marry an IS fighter but was later rescued by her mother will appear in court Friday on terror charges, Dutch prosecutors said.
As a proportion of their populations, Belgium and Denmark are the biggest contributors to the jihad in Iraq and Syria, although France -- which has Europe's largest Muslim population -- has sent the largest overall contingent.
"France is particularly affected by this phenomenon in part because networks still exist that sent volunteers to fight against the Americans in Iraq after 2003," said Louis Caprioli, a former head of counter-terrorism for the French intelligence service.
He also pointed towards the "Tabligh" movement of Islamic preachers that has been "very active in French towns and suburbs since the mid-1990s" -- providing a base from which some members of the community moved on to more radical off-shoots.
"Its efforts to re-Islamise young people of second and third-generation immigrant communities is now bearing fruit," said Caprioli.
He said even the converts to Islam were often in close proximity to these immigrant communities, although he emphasised there were multiple explanations for the burgeoning numbers of radicalised youth, not least "the extraordinary quality of Islamic State communications, which perfectly exploit all the tools of the Internet."