World has changed in surprising ways

That judgment has been vindicated. But it is the nature of the change that has surprised. For it was the reaction to terrorism rather than the terrorism itself that mattered most.

In the aftermath of 9/11,the administration decided that the war on terror would be the defining principle of US foreign policy. Within months,a war on Afghanistan was launched to go after the safe havens from which al-Qaeda had launched its attack. Despite swift success against the Taliban,that war is still dragging on.

The response to 9/11 did not stop with the Afghan invasion. Fairly swiftly,it became clear George W Bush,then US President,was also intent on toppling Saddam Hussein in Iraq.

Two big neoconservative ideas defined the Presidents war on terror and led to the Iraq war.

The first was the doctrine of pre-emption. The neocons argued that because the consequences of a large-scale terror attack 8211; particularly with nuclear or biological weapons 8211; would be catastrophic,the US would be justified in taking pre-emptive military action to head off such a threat. This was a search for absolute security defined by the 1 per cent doctrine of Dick Cheney,the vice-president,which held that if the US was faced with a 1 per cent threat that terrorists could acquire weapons of mass destruction,it should act as if it was a 100 per cent certainty.

The second big idea was that the terrorism of 9/11 was the product of a sick and despotic political culture in the Arab world and was an attack on freedom. In response,the US would go on the counter-attack and adopt a freedom agenda. As President Bush put it,the US would act decisively to bring the hope of democracy,development,free markets and free trade to every corner of the world.

In retrospect,however,it looks as if the threat of terrorism particularly to the US was overstated in the aftermath of 9/11. There have been further big terror attacks linked to al-Qaeda in Madrid,Bali,London,Mumbai and elsewhere but the monstrous attack on US mainland that was feared by so many has not materialised.

The attacks on New York and Washington in 2001,horrifying as they were,did not shake US dominance of the global political and economic system. On the contrary,in the immediate aftermath of the Iraq and Afghan wars,the Bush administration and its supporters felt more confident of US power than ever. However,by 2008 it was clear that early military victories in Iraq and Afghanistan had given way to something much more inconclusive,bloody and frustrating.

Then,just before Barack Obama took office in 2008,the global financial crisis hit. Its aftermath,and the change in the balance of global economic and political power it has provoked,have undermined the assumptions about US power on which the war on terror was based.

The US has managed to cut its military commitment to Iraq. But Obama reluctantly agreed to a new troop surge to combat a deteriorating situation in Afghanistan. He was also unable to fulfil his campaign pledge to close the Guantánamo prison camp for terrorist suspects. And he has increased the use of controversial drone attacks on al-Qaeda bases in Pakistan.

The Arab spring has provided support for the neoconservative notion that the Arab world could not and should not be exempt from a global trend towards democracy. But it has also illustrated that durable change is much more likely to come from within,than via US intervention.

In the short term,the changes have heightened US anxiety about the emergence of radical movements and terrorist safe havens in a destabilised Middle East.

By contrast,the killing of Osama bin Laden in May provided the US administration with a closure that eluded the Bush administration. But it has not yet ended the global war on terror or the enormous claim it makes on US resources.

Even as he announced he was sending more troops to Afghanistan,Obama fretted: We simply cannot afford to ignore the price of these wars an admission Bush would never have made. Defence cuts are on their way.

The President knows that as the US pours money and resources into the global war on terror,the truly epoch-making changes of our time are taking place in east Asia. The rise of China and India as economic powers and the relative decline of the US will ultimately shape the next century far more than the terrorist threat.

The violent Islamist militancy highlighted by 9/11 still has the potential to do enormous damage. But the idea that the main geopolitical trend of the next century will be the creation of a global Islamic caliphate while a popular notion in Waziristan is a fantasy.

Indeed one consequence of 9/11 is that it may have persuaded the US to spend a decade pouring vital resources into combating the wrong threat.

Gideon Rachman, 2011 The Financial Times Limited