There are lots of opinions floating around about ISIS and which military strategy would be best to defeat it. Graeme Wood’s piece in the March Atlantic is an interesting one and very informative.
“One way to un-cast the Islamic State’s spell over its adherents would be to overpower it militarily and occupy the parts of Syria and Iraq now under caliphate rule. Al‑Qaeda is ineradicable because it can survive, cockroach-like, by going underground. The Islamic State cannot. If it loses its grip on its territory in Syria and Iraq, it will cease to be a caliphate. Caliphates cannot exist as underground movements, because territorial authority is a requirement: take away its command of territory, and all those oaths of allegiance are no longer binding.”
But, for now and the long run, Gordon Brown (“prime minister of Britain from 2007 to 2010 and a U.N. special envoy for global education”) writes about a unique experiment already underway in Beirut.
[The strategy of the Islamic State is to “capture the rebelliousness of youth, their energy and idealism, and their readiness for self-sacrifice,” according to its own propaganda. Central to this worldview, as one former hostage held by young Islamic State extremists bore witness, is “the belief that communities cannot live together with Muslims” and “that there is a kind of apocalyptic process under way that will lead to a confrontation between an army of Muslims from all over the world and non-Muslims.”]