The Islamic State's beheading of James Foley garnered the jihadi outfit the notoriety it had been aiming for, thanks to the internet. But such was the universal revulsion at the video, the terror group may have unwittingly signed its own death warrant, too.
As a flood of sensational stories in the US media claimed they were gearing up to blow to smithereens entire American cities, the Obama administration hinted it would soon be targeting the Islamist State's leadership with air strikes. Britain, meanwhile, prepared new legislation to make it easier to imprison home-grown
jihadists.
The Islamic State's funder, Qatar, for the first time publicly denounced its Frankensteinian monster, and - realising its international reputation was in free-fall - was reported to have paid a ransom to quickly secure the release of another captive American journalist.
Khaled Mashaal, the Qatar-based leader of Hamas - which at the outset of the Syrian Civil War declared its support for the Islamists - gave a TV interview in a desperate bid to distance his own group from the atrocity.
Turkey, too, witnessed unprecedented diplomatic pressure to close its border with Syria, through which foreign-born jihadists have been pouring into the war-torn country.
Egypt, which under deposed Islamist president Mohammed Morsi had called for all able-bodied Muslims to join the Syrian jihad, flatly announced that the country now supports neither the Syrian regime nor the opposition.
Egypt's foreign minister was then dispatched to the Saudi commercial capital, Jeddah, to join his counterparts from Saudi Arabia, the UAE and Qatar, as well as an adviser to Jordan's foreign minister.
Under discussion: the Syrian conflict and "challenges including the rise of terrorist extremist ideology". Panic was evident in their final joint statement, which highlighted - crucially, with terror-sponsor Qatar's approval - the need to cut off the jihadists' funding to "preserve security and stability" in Arab countries.
The Islamic State simultaneously took the main military air base in northern Syria, and does now look capable of overthrowing the Assad regime. Seizing the moment, Damascus told Washington that it was willing to fight alongside the US to crush the Islamist insurgency.
However, in the West it was left to a former British foreign secretary, Sir Malcolm Rifkind, to state what is now indeed blindingly obvious to all but the most blinkered observers. Namely, that there is a case for collaboration with Bashar al-Assad because, in times of war, an enemy's enemy is a friend.
Predictably, the British government dismissed his proposal, itself having narrowly lost a parliamentary vote last year that threatened the Assad regime itself with air strikes. To be sure, the political cost of such a humiliating U-turn would be incalculable.
At the same time, its own pro-interventionist narrative - of supporting "moderate" as opposed to "radical" Islamists - now has as much credibility as claims that Saddam Hussein had weapons of mass destruction.
Even Saudi Arabia has washed its hands of the Islamic State. And Jordan's King Abdullah is having to make ever greater concessions to the Muslim Brotherhood in his country in order to stave off an Islamist revolt there.
Should the Assad regime fall, Jordan's monarchy will surely crumble; and there is a real risk of an Islamist uprising in Saudi Arabia, just as Islamist militias take control of Libya.
The new caliphate, and its viciously antisemitic footsoldiers, would then be free to concentrate its considerable military might on their most treasured goal: the destruction of Israel.
One hopes, then, that Sir Malcolm's wise advice will be more intelligently considered, as - despite the official denials - the real wheeling and dealing between the West, Arab states and the Syrian regime gets under way behind the scenes.
President Al-Assad may indeed be a kind of Cerberus - but the entrance to hell is just behind him.
