Since surrender is out of the question, we have to accept that the Age of Terror may very well go on for decades which would test our reserves of stoicism. The Irish Republican campaign against Britain was on a much smaller scale, yet still lasted 30 years. It ended because the IRA had specific political goals thus there was a basis for negotiation. As long as Isis's raison d'etre remains the universal imposition of its ideology and the annihilation of non-believers and apostates, this conflict cannot be resolved at the negotiating table.
You can argue that late 20th century mass immigration was unwise or even that it amounted to a betrayal on the part of the political elite, but it's purely academic. France has 4.7 million Muslims, 7.5 per cent of the population, and they're not going anywhere. The challenge for France and other European nations with large Muslim communities is to break down the so-called "soft apartheid" that marginalises them before it's too late.
Integration and tolerance are two-way streets; disavowing jihadism requires more than press statements. Muslim communities have to be more forthright in their commitment to Western values and less indulgent of those in their midst who preach and practice hatred.
As Maajid Nawaz, head of the London-based counter-extremism think-tank Quilliam, wrote this week: "Until now the bitter truth that our Muslim populations have been subjected to decades of sustained Islamist propaganda by those who live among them has gone almost totally ignored. The long-term solution cannot continue to ignore this truth."
Unlike al-Qaeda, Isis is a territorial entity and therefore susceptible to a conventional military campaign. But that must be in the form of a co-ordinated, strategically coherent international effort as opposed to the current piecemeal, reflexive sallies. And as Barack Obama has pointed out, if the nations in the region that have suffered far more than the West and have the most to lose if Isis isn't defeated don't commit to this fight, then any victory will be in name only and jihadism will swiftly re-emerge under another name and another flag.
While we could do with fewer beside-the-point lectures about our supposed indifference to bombings in Baghdad and Beirut and less hand-wringing over our government turning into Big Brother, our best defence is liberal, secular, inclusive democracy and the hope it offers to those who can only dream of living in a society like ours.