Fran?ois Hollande, France’s president, rightly called it “an act of exceptional barbarity . . . against freedom of expression”. But the murder on Wednesday of 12 people at the Paris offices of Charlie Hebdo, a satirical magazine, will not surprise anyone familiar with the rising tensions among France’s 5m or more Muslim citizens and the poisonous legacy of French colonialism in north Africa.

For now, the perpetrators are unidentified. We need to keep in mind that the worst terrorist outrage in Europe of recent years, the murder of 77 people in Norway in 2011, was committed not by Islamist militants but by a far-right fanatic, Anders Behring Breivik.

Like other politically motivated attacks, from 9/11 to the killing last May of four people at the Jewish museum in Brussels, the atrocity at Charlie Hebdo was despicable and indefensible. Among the first to condemn it was the French Council of the Muslim Faith, which termed it “a barbaric act against democracy and freedom of the press”.