Alongside strong reactions of the French President and fellow world leaders, thousands of people have taken to the streets worldwide to show solidarity.
But as shock gives way to anger, and as a manhunt is under way to find the perpetrators, questions mount about the reasons for the Charlie Hebdo attack, its principal targets, what can be done, and whether it can happen again.
On the face of it, this was an attack on a French satirical magazine best known for its provocative cartoons, its inflammatory journalism and its radical politics. Charlie Hebdo has been no stranger to controversy. Its editorial staff have gone to great lengths to sustain its satirical irreverence, to the point that its offices were firebombed in 2011, and its editor lived under police guard. Radical Islam was a regular target of its cartoonists’ pens, but so too were other religions, politicians and political parties of all stripes, teachers, smokers and many more besides.
This was also an attack on values: on freedom of expression, on freedom of the press, and on traditions of democracy, as David Cameron and many others were quick to argue.
But this was also, very squarely, an attack on France. The country has faced threats from Islamist terrorism at least since the 1990s, and has been under explicit threat since 2005.
From 2006, threats have been linked under the banner of al-Qaida, Moreover, despite the efforts of the French security services, attacks on mainland France as well as on French interests abroad have taken place. The gunman Mohamed Merah killed seven, including children, in 2012; while only days after the murder of Fusilier Lee Rigby in London in 2013, a French soldier was repeatedly stabbed on the outskirts of Paris by a radicalised perpetrator. Last month, there was a spate of attacks on members of the public at Christmas markets in Nantes, Dijon and Cannes, although motives behind the attacks were unclear.
These threats are exacerbated by developments in French domestic and foreign policy, whose effects are disproportionately perceived to be felt by Muslims.
At home, the law on secularism in France and the ban on wearing overt religious symbols have caused particular tensions. And since 2011 it has been illegal to wear a full-face veil in public places in France, a measure clearly aimed at those wearing some styles of Islamic dress.
Abroad, France was a contributor to international efforts against al-Qaida in Afghanistan from 2001, though not to the invasion of Iraq from 2003. France under former president Nicolas Sarkozy led in the war in Libya in 2011, and under François Hollande, the current occupier of the Elysee Palace, carried out a military intervention in Mali in 2013 to push back Islamic militants threatening the unity of that fragile state. Since 2014, France has taken part in international air strikes against the forces of Islamic State (IS).
The external and domestic consequences of these policies have combined in the fact that radicalisation in France was a severe problem by last autumn, and almost 1,000 French citizens had joined or sought to join IS fighters in Iraq and Syria.
Despite the long-standing terrorist threat to France, though, the attack on Charlie Hebdo is of a different scale and significance.
In contrast to the Merah crimes in 2012 for instance, and the recent Christmas market attacks, Wednesday’s assault was targeted, discriminate, deliberate, well-planned and effectively – murderously – implemented. It was calculated to achieve maximum publicity and worldwide impact.
So what can President Hollande and his government do? In short, not much. Hollande is stuck between a rock and a hard place. The President, despite his anger, is politically weak. Halfway through a presidential term which many will prefer to forget, his poll ratings are dire and to date he has lacked authority and credibility to give an effective lead.
Domestically, French society is fractured and divided. Traditionally having a large immigrant population, France’s policies of “assimilation” have failed to integrate different communities. Economic disparities, limited prospects and deprivation have characterised the suburbs where populations have clustered. Anti-Semitism, as well as discrimination against Roma and Islamophobia, are all on the rise. Support for the Front National, under Marine Le Pen, continues to grow.
Externally, Hollande has sought to establish a strong foreign policy for France based on military interventions and strong rhetoric, but operations in Mali and air strikes in Iraq have stoked the problems faced, not reduced them. But backing down is not an option: this would be to give in to terrorists, and Hollande lacks the political capital to reverse his foreign policy without undermining even more any credibility he might still retain.
And can it happen again? Sadly yes. Wednesday’s events and vigils have been followed yesterday by grenade attacks and gunshots at Muslim places of worship in various parts of France, and a policewoman has been shot dead in the southern outskirts of Paris. It is not clear whether these attacks are linked, but they constitute a collective assault on a fractured society with embattled political leadership and growing inter-societal tensions and radicalisation.
France is facing severe challenges, in short, whose successful outcomes are neither imminent nor clear.
• Dr Rachel Utley is a lecturer in international history at the University of Leeds.