There is a feeling of inevitability about the attack in Paris.
The likelihood must be that the killers were Islamic fanatics, the murder of the journalists and police underlining the degree to which the ferocious religious war being waged in Iraq and Syria now affects all of the world.
That conflict has provided an ideal seedbed for Islamic extremism.
It was culpably naive to imagine that sparks from the Iraq-Syrian civil war, now in its fourth year, would not spread explosive violence to Western Europe. With thousands of young Sunni Muslims making the journey to Syria and Iraq to fight for Isis (Islamic State), it has always been probable that some of them would choose to demonstrate their religious faith by attacking targets they deem anti-Islamic closer to home.
One way of measuring the spread of al-Qaeda-type groups is to look at suicide bombings over the past week. Several of them have inflicted heavier casualties than at Charlie Hebdo. In the Yemeni capital, Sana'a, on Wednesday, a suicide bomber driving a minibus packed with explosives killed 33 police cadets. In Iraq, another suicide bomber killed 23 soldiers and pro-government Sunni tribesmen in a town in Anbar province northwest of Baghdad.