Islamic State sees beheadings as a step to the apocalypse
Experts say an ancient prophecy of a final showdown drives much of the militant group's actions
The world's most potent terror group is also its most savvy. In its 18-month existence, Islamic State (IS) has imposed its old-world view of Islam using very modern means. Slick production, an eye for a camera angle and high-definition horror have done as much to showcase the group - and further its aims - as its rampage across Iraq and Syria.
Almost every move IS has made has been chronicled, either on shaky mobile phones or with slicker production values. IS may eschew much of the modern world, but it certainly studies its enemy. And in what is its biggest punt, the group appears to have gambled that it can call the bluff of its most formidable foe.
On extremist forums and within IS, debate rages about how the US will respond to the beheading of two of its citizens, and what Britain and Europe may do if their nationals are harmed. A growing school of thought is that the deaths of James Foley and Stephen Sotloff have done what three blood-soaked years in Syria and Iraq failed to do: galvanise war-weary Western leaders and their sceptical publics to acknowledge a fast-growing enemy that may eventually point its turrets their way.
Opponents of the brazen violence say that while such tactics have a strong shock value, they also stir sleeping giants. And if IS is to continue its quest for dominance, having superpowers collectively enraged so soon might not help further such goals.
The group has enormous momentum; militarily it is manoeuvring on three fronts at once - something far beyond the capabilities of the Iraqi and Syrian armies. Along the way, it is collecting large numbers of Sunnis. Some are being press-ganged, others are joining from fear, and some from a conviction that the jihadis share their values and are acting out prophecies.
Whatever their motivation, Iraq's Sunni minority shares a sense of being estranged from the political process since Saddam Hussein was ousted and Shiite Iran established itself as a post-occupation power. Syria's Sunni majority has been partly subservient to a Shiite-aligned Alawite regime for three decades longer. Together they make a formidable support base.
With a new caliphate declared, the next step will be decided by the self-styled caliph, Abu Bakr al-Baghdadi, and a tight-knit military council. Some who study IS closely say Baghdadi is aiming for an apocalyptic showdown that he wants to bring on sooner rather than later. Interpretations of Koranic teachings underpin all of what he does.
And high on the list is a 1,400 year-old-prediction that Muslims and Christians will fight a pre-apocalyptic battle in a place called Dabek. Since establishing themselves as a force in northern Syria in May last year, IS members have focused on a hamlet some 50km south of the Turkish border called Murj Dabek. This, to many among IS, is the war's ground zero.
"Baghdadi wants to bring the Americans into a war with him so he will prove what was written in the Koran and the prophecies that [Christians] will fight against the Muslims," said a leading Iraqi expert on IS, Hisham al-Hashimi. "He wants to prove that he is the leader of Muslims. Having the Americans bomb him is not at odds with spreading the caliphate. His dream is a real jihad against the Crusaders."
Baghdadi does not fear the Arab world's armies. He has tapped into the ruins of a body politic that has spectacularly failed to share power or respond to the will of the people. He knows from his time in Iraq, in US prisons and on the battlefield, that to be realistically confronted, the US or another power will need to ally with local backers.
He also knows that without an occupying army - something Barack Obama seems repulsed by - it will be difficult to splinter his Sunni support base.
"There are military leaders working with him, former Saddam henchmen," said one former middle-ranking IS member who left the group before its advances into Mosul and Tikrit.
"They were not with us then. They thought we were a bus that they wanted to get to their destination. But now, from what I know of them, they are just as ruthless, just as committed. These people are running the war in places like Tikrit. Even if they part ways, they will help Islamic State win."