This, I suspect, has been a key factor in ISIS’s success to date. It certainly plays a role in encouraging the susceptible to emigrate to the “caliphate” or launch their own attacks in their home countries. It has put ISIS at the top of the terrorist lists, although it is one of dozens of equally murderous insurgent groups inspired as much by power-seeking as by the Islam they use as an excuse.

It is why the media coverage focus on ISIS atrocities and apocalyptic propaganda and the politicians’ desire for ever-fewer checks on their powers have resulted in unrealistically high fear levels in Europe and North America, and consequent losses to the civil liberties and democracy we are ostensibly committed to promulgating.

It is also why, even if all present ISIS members were somehow wiped out, no “mission accomplished” bravado will mean an end to terrorism. Terrorism is, after all, a tactic various power-seekers have used for millennia, by no means confined to “Islamic fundamentalist” movements or the existence of modern communications and weapons.

It’s based on the sad fact that you can frighten many by killing a few at small cost but with plenty of drama. It’s based on the reality that a relatively weak force can wreak havoc with hit-and-run attacks while evading the militarily and politically strong’s attempts at suppression. Groups with ambitions much greater than their means adopt terrorism in the hope that their political opponents will be frightened and disorganized, and thus weakened enough to collapse. or at least be willing to compromise with the group.

In the case of ISIS, the ideologues are not open to compromise – they want an empire under their own interpretation of sharia – but many in the group are less rigid: they want political independence within a region that was arbitrarily carved up by foreign powers, revenge against past oppressors, an end to foreign intervention, or simply access to power and money for themselves. Realistically, some of those motives are more susceptible to negotiation than others but a blanket “we don’t negotiate with terrorists” seems like a way to ensure the group coheres rather than weakens and falls apart due to internal stresses.

Meanwhile, reliance on more military violence in the MENA region and increasingly heavy-handed “security” laws at home seems to be a factor in mobilizing support for ISIS by the angry disaffected, not to mention increasing the fear levels of the general public in a way ISIS clearly wants.