The brutal killings in Paris come on top of the downing of a Russian airliner in Sinai, the bombing of a Hizbollah stronghold in Beirut and an attack against Kurds in Ankara. Some 500 have been killed in the past few weeks, and many more injured. Isis has claimed the first three, and is suspected of the fourth.

So how should we understand the strategy of the Islamist militants? Do they want to draw foreigners in further or frighten them away? I am not sure that is how they are thinking.

What Isis wants is continuing turmoil in Syria, and in Iraq too, so that it can control territory and resources to build up its “caliphate”. It is not seeking to overthrow Bashar al-Assad — the Syrian president is useful as a target of Sunni anger, and there has been tacit co-operation between Isis and the regime. They avoid direct conflict, trade in oil and both target the more moderate militias.