PARIS (AFP) - A horrified France was grappling with a new reality on Thursday in which hundreds of its citizens are openly joining extremist groups and directly calling for attacks on their homeland.
A new video from the Islamic State in Iraq and Syria (ISIS) group released on extremist 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 ISIS, which has seized large parts of Syria and Iraq.
It follows the appearance of two other French militants - identified as 22-year-olds Maxime Hauchard and Mickael Dos Santos - in a brutal ISIS execution video released at the weekend.
Defence Minister Jean-Yves Le Drian announced on Wednesday that France would step up its campaign against ISIS, 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 ISIS fighters around the northern Iraqi city of Kirkuk on Tuesday.
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 radical group in Iraq and Syria, with 375 currently there.
Prime Minister Manuel Valls said Wednesday that "close to 50" French citizens or residents of France have been killed in the conflict zone.
"So we know the dangers and, sadly, we are not surprised to learn that French citizens or residents of France are found at the heart of these cells and taking part in this barbarity," said Valls.
Figures published in the Le Monde newspaper this week found almost a quarter of those who left to join ISIS are converts to Islam, with many coming from jarringly everyday French backgrounds.
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.
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.
French authorities say the other French militant in the video, Dos Santos, is of Portuguese origin but born in the French riverside town of Champigny-sur-Marne.
He was part of a network of radical young men in his neighbourhood and is believed to have left for Syria in the autumn of 2013, according to a government source.
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.
As a proportion of their populations, Belgium and Denmark are the biggest contributors to the Islamist insurgency 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."