When the history books come to be written, someone will doubtless compare the self-immolation of the Tunisian street-seller Mohamed Bouazizi on 17 December 2010, which sparked the wave of Arab uprisings, with the shot fired by the Yugoslav nationalist Gavrilo Princip that killed the Archduke Franz Ferdinand of Austria in Sarajevo on 28 June 1914.
Each was a single act that no one could have foreseen would lead to the appalling carnage that followed. And each reshaped the world, destroying great political powers and sowing the seeds for future instability.
When peace was restored to a shattered Europe in 1918, the Austro-Hungarian and Ottoman empires had been destroyed. The rise of Germany had been halted; the Russian revolution had ended centuries of Tsarist rule, and the US had emerged as a major global power.
There is no sign yet of peace being restored in the Middle East; in fact, quite the reverse. Yet old regimes have been either swept away (Tunisia, Egypt, Libya), by a combination of popular uprising and external military force, or forced into a brutal suppression of internal dissent fuelled by external meddling (Syria).
In 1914, Germany, Austria-Hungary, Russia, France and Britain went to war in defence of their national interests and in an attempt to exert their control in Europe. A hundred years on, we see different regional powers -- Iran, Saudi Arabia, Turkey, Qatar, UAE -- behaving in exactly the same way.
And there is a certain grim irony about the way borders are now being redrawn, as jihadi extremists establish their trans-national medieval caliphate, and the Kurds formalise their own nation state. After all, it was in the aftermath of the First World War that the current borders were originally drawn. As the former UN diplomat and Foreign Office adviser Michael Williams (Lord Williams of Baglan) has pointed out: "Throughout the Middle East the presence of the state is fast weakening … In the immediate post-colonial order dictated by Sykes–Picot, strong states prevailed in the Middle East. That era is fast disappearing."
The rise of the movement that now calls itself the Islamic State has rightly been seen in large part as a Sunni reaction against Shia (or Alawite in Syria) supremacy. But it cannot be confronted without recognising that it is also a symbol of Saudi determination not to see Shia Islam, as promoted by Riyadh's rival Iran, become the dominant force in the region. (Think of it as the Roman Catholic church resisting the rise of Protestantism in 16th and 17th century Europe.)
It may be that IS fighters receive no direct support or funding from the Saudi government or from the clerics of the Wahhabi sect that underpins the house of Saud. But their brutal, extreme version of Islam stems directly from what the distinguished Middle East analyst David Gardner of the Financial Times recently called the "radical bigotry of Wahhabi absolutism". In a piece published last Friday, Gardner wrote: "Saudi Arabia not only exports oil, but tanker-loads of quasi-totalitarian religious dogma and pipelines of jihadi volunteers."
So here's a challenge for all those Western governments, in particular the US, UK and France, who sell billions of dollars worth of weaponry to the Saudis and other Gulf potentates every year. Will you publicly demand that they disown the murderous zealots now rampaging through Syria and Iraq and cut off the financial support that flows to them? Will you risk valuable defence sales to save the lives of thousands of Yazidis and others who are now being mercilessly persecuted by the region's fastest rising new power?
The former head of MI6, Sir Richard Dearlove, was quoted recently as having been given an ominous warning by the former head of Saudi intelligence and former Saudi ambassador in Washington, Prince Bandar bin Sultan. "The time is not far off in the Middle East, Richard, when it will be literally ‘God help the Shia’. More than a billion Sunnis have simply had enough of them." The clear implication was that the Saudis would do nothing to impede the slaughter.
According to a report of a speech that Dearlove gave at the Royal United Services Institute last month, "he does not doubt that substantial and sustained funding from private donors in Saudi Arabia and Qatar, to which the authorities may have turned a blind eye, has played a central role in the Isis surge into Sunni areas of Iraq. He said: 'Such things simply do not happen spontaneously.'"
There's no mystery about why more isn't being made of this. According to The Guardian, Saudi Arabia is the recipient of more British weapons than any other country and is the biggest foreign customer, after the US, of BAE Systems, the UK's largest arms company and biggest manufacturing employer.
So what can be done to halt the IS advance? Bombing it, according to one detailed recent analysis, "is unlikely to turn around Iraq … its fragmented condition has given the self-proclaimed [IS] caliphate the opportunity to establish a hub of jihadism in the heart of the Arab world …
"The jihadist army … is now brimming with confidence, emboldened by blood and treasure … exploiting sectarian and tribal faultlines in Arab society, petrifying communities into submission and exploiting the reluctance of Washington and the West to intervene more robustly in the civil war in Syria."
Shipping more arms to the Kurds will probably help at the margins; it may even halt the advance of the IS legions. But we should be in no doubt: we, the West, are back in Iraq. Perhaps the consequences of not helping anti-Assad rebels in Syria before the rise of the jihadis are now translating into a realisation that in order to stop the bad guys, you sometimes have to get stuck in and accept the associated risks.