By Jonathan Freedland
On one side stand Tony Blair, Jack Straw and a good chunk of the media. On the other Chatham House and, according to yesterday's Guardian/ICM poll, two-thirds of the British people. The issue that divides them is, once again, the Iraq war.
Our political culture seems fated to return to this sore spot. Whether it's the David Kelly affair or the attorney general's advice, one way or another British politics comes back to Iraq. Now the question is forced by the London bombings: what role, if any, did the invasion of Iraq play?
The prime minister is insistent: the two have nothing to do with each other. Al-Qaida was at war with the west long before the Iraq adventure; and if al-Qaida cares so much about Iraqi civilians then why is it killing so many of them, including children, through suicide bombings? Turning up the volume, the foreign secretary sought to drown out the Chatham House report - which said the Iraq war had given a "boost" to al-Qaida - by declaring: "The time for excuses for terrorism is over."
Meanwhile, those who see Iraq as a cause of the July 7 atrocities are becoming bolder. In the immediate aftermath of the bombings only George Galloway dared to make the link. He was shouted down, chiefly on grounds of taste, criticised for continuing a political argument when the hour called for mourning. But since then he has found some unexpected allies.
On Monday it was Chatham House. Yesterday it emerged that the Joint Terrorism Analysis Centre (Jtac) - a group that combines the police, MI5, MI6 and GCHQ - had filed a report three weeks before 7/7 that cited Iraq as a "motivation and a focus of a range of terrorist-related activity in the UK".
Blair could try to wave that aside, noting that the geniuses of Jtac had also concluded that no group in Britain had the "intent and the capability" to mount an attack. More tricky are the 64% of Britons who told our pollsters that they see the PM's decision on Iraq as bearing some responsibility for the London bombings; they can't all be fellow travellers of Osama bin Laden.
And yet it would be a mistake for this current dispute to collapse into a mere rerun of the old Iraq debate. The issues are different now - and more nuanced than either side might like to admit.
For those who opposed the 2003 conflict, it is tempting to cast Iraq and the whole panoply of US-UK actions after 9/11 as the decisive factor in the bombings. There is certainly no shortage of evidence. For one thing, Britain had never been the target of jihadist violence before 9/11 (even if the US had). Second, Britain's own intelligence agencies - not only the anti-war movement - predicted just such a causal link, warning that the threat from al-Qaida would be "heightened" by an invasion. (That threat became sharper because British and American military energies were diverted away from al-Qaida and on to Saddam).
Third is the evidence of our own eyes. Iraq has become what Afghanistan was before 2001, one huge university campus of terror. Analysts used to need a microscope to find links between Saddam's Iraq and international terror - usually lighting upon addresses for retired killers in suburban Baghdad. Now the place is positively crawling with active jihadists planting bombs, beheading hostages and plotting 57 varieties of mayhem for Europe and the west. In trying to root out a couple of weeds, we set the entire garden alight.
Above all, Iraq's connection to the London bombers is the obvious one: it has served to anger and radicalise a generation of young Muslims across the globe. Peter Taylor, the veteran documentary film-maker who spent decades studying Northern Irish terrorism, has just completed a BBC series, The New Al-Qaida, which starts next Monday. After a year spent talking to Muslims in Spain, Morocco, Pakistan, the US and the UK, he says: "The one word that comes out loud and clear is Iraq. There is no question that Iraq is the prime motivating factor."
So Iraq is central. But it is not the whole story. For, as Taylor explains, al-Qaida is not like Eta or the IRA - organisations with a clear, single goal. It is not simply a troops-out movement, demanding nothing more than a withdrawal from Afghanistan and Iraq and justice for the Palestinians. It is not the armed wing of the Stop the War Coalition.
Its aims are rather different. Central to its ideology is the reintroduction of the caliphate, an Islamic state governed by sharia law that would stretch across all formerly Muslim lands, taking in Spain, Morocco, north Africa, Albania, Turkey, Saudi Arabia and the Middle East, as well as Pakistan, Indonesia and the Philippines. Plenty on the left tend to skim over this stuff, dismissing it as weird, obscurantist nonsense - and imagining it as somehow secondary to al-Qaida's anti-imperialist mission.
That's a big mistake. For it is this animating idea which helps to explain al-Qaida actions that otherwise make no sense. Why did the Madrid cell that staged last March's train bombings continue to plan attacks, even after Spain's new government had begun withdrawing from Iraq? Perhaps because al-Qaida wants to recapture at least part of Spain for Islamist rule. Why did it bomb a nightclub in Bali? Partly to attack western tourists, of course. (Taylor says the bombers thought the clubbers would be American, not Australian.) But its chief aim was to destabilise Indonesia, which it wants to place under Islamist rule as part of the yearned-for caliphate.
In other words, al-Qaida has a programme that predates and goes beyond Iraq. It seeks to end all western presence in those lands it deems Islamic. That's why it has, over the years, targeted France and Germany as well as the US and the UK. When Tony Blair asks "What was September 11 the reprisal for?" he should know the answer. It was for eight decades of US-led, western meddling in territory that al-Qaida believes should be Muslims' alone.
This is the ideology that defines al-Qaida and which explains why it was in business from 1993 and not just 2001 and after. Tellingly, those who monitor Islamism in Britain say the big surge in growth of extremist groups came not after 9/11 or Iraq but in the mid-1990s - with Bosnia serving as the recruiting sergeant. In the same period Chechnya, Kosovo and Israel-Palestine all came into play - again predating Iraq.
What it adds up to is a more mixed picture than either Blair or the anti-war movement has allowed. Iraq has played a key part - of course it has - in angering large numbers of young Muslims, pulling them towards an extremist message once confined to the lunatic fringe. But that message is not only about Iraq, Afghanistan or even the Israeli occupation of the West Bank and Gaza - and we delude ourselves if we think it is.