Last week the French interior minister, Bernard Cazeneuve, announced the total so far of apartment searches (1233), detentions (165) and charges preferred (124) since the state of emergency came into force shortly after the killings on 13 November. Dividing the country’s ‘Muslim’ population by the number of detentions we arrive at a figure of one for every 30,000 or so: this is not an anti-Muslim witch hunt. Nonetheless the emergency has been extended for three months and yesterday the total of arrests leaped, with 200 or more after the COP21 demonstrations in Paris – a big, scheduled march having been banned under the emergency – turned rough.

It’s war time again. Earlier this month the Commons Foreign Affairs Select Committee (FAC) noted that legal opinion is at best divided on the legality of whacking Islamic State without Chapter VII support, but last Friday the UN passed resolution 2249 enjoining member states to take ‘all necessary measures’ – UN-speak for military action – against IS. David Cameron will probably seek and get Commons approval for war next week, a move that’s already had the spin-off benefit of splitting Labour’s Corbynites and hawks.

After a busy night for the police, France woke on Monday to news that more than 20 people had been taken into custody and 104 placed under house arrest. In the evening Hollande proposed a raft of measures to the General Assembly and the Senate involving tweaks to the constitution that enable the government ‘to manage a state of crisis’ and deal with the new reality (‘we are at war’). He also proposed 5000 more police and soldiers on the payroll by 2017, 1000 more border staff, 2500 new prison staff. More citizens with dual nationality would have their French nationality removed and be subject to ‘expulsion’.

The Iraq National Museum reopened on 28 February. Many of the treasures of ancient Mesopotamia are in the British Museum or the Pergamon in Berlin, or were lost to looting after the 2003 invasion, but some wonderful objects are now on show in Baghdad. I visited last week. As I was looking at pieces of Iraq’s great civilisations in glass cases, the extremists of Daesh (as the Islamic State is known in Arabic) were smashing up the original sites for being idolatrous.

There isn't much primary source material on the foreign women who have gone voluntarily to Syria and Iraq and chosen to live under the Islamic State, alongside the thousands of women Isis have kidnapped, beaten, raped, forced to convert and sold into sexual slavery. We know the places the volunteers have left but can only speculate as to why.

No one really dwells on the question of why so many young men from Europe, Canada, Australia, even China, are going to fight in Syria and Iraq with the so-called Islamic State (Isis), or with other Islamist militias. The New York Times recently published a map showing which countries the foreign volunteers come from. The numbers are slippery and often contradictory, but the foreign presence in Syria and Iraq is reckoned at around 17,000 fighters. The biggest contingents are from Chechnya and the North Caucasus (around 9000) and Turkey (1000). There are also 400 from Kosovo. But 1900 come from Western Europe (700 from France, 340 from Britain, 60 from Ireland), 100 from the US, and between 50 and 100 from Australia.

It was difficult at times to recall that the military intervention in Iraq being debated in the House of Commons involves sending six Tornadoes to bomb suspected Isis positions. It is very much a symbolic action from the British point of view. MPs seemed to be trying to grapple with the complexity of what is happening but not quite succeeding. Cameron and others made great play with the idea that military action is in support of a new, inclusive Iraqi government, when in fact it is as Shia-dominated as the old. Its most effective military strike force are Iranian-managed Shia militias but they, along with the Iraqi army, terrify the Sunni.

The killing of James Foley by Isis caused an upsurge of international revulsion and condemnation with harsh words from the US defence secretary and others. But the Obama administration is trying hard not to be sucked into a war that could be more serious than the US invasion and occupation of Iraq between 2003 and 2011. What Isis showed by Foley's very public murder is that it will always raise the stakes in any confrontation with the US and anybody else. It trumped America's reassuring portrayal of the recapture of Mosul Dam by the Kurds aided by US air strikes as a sign that Isis could be defeated.