Europeans instinctively wish to manage risk while the US still strives to eliminate its vulnerabilities altogether, writes Jonathan Eyal. The sole remaining superpower has changed its priorities, overturning most of the assumptions.
Prudence, commonsense or even just a casual glance at various crisis locations would suggest that the world has not changed fundamentally since September 11th last year.
The Palestinian-Israeli conflict remains as intractable as ever. The Middle East as a whole is still a powder keg. The Taliban regime has been dismantled, but the future of Afghanistan remains uncertain. Disease and economic decay still afflict Africa, and Latin America's economic and political institutions are shakier today than they were a year ago.
Even the "war on terrorism" remains for the moment a highly-qualified success: the main organisers of the atrocities against the US have been deprived of permanent bases and training camps, but they have escaped capture and are assumed to be planning further attacks.
Yet appearances are deceiving for, in one crucial respect, the world today is different: the US, the sole remaining superpower, has changed its priorities, overturning most of the assumptions which underpinned global strategic arrangements.
For many decades ordinary Americans believed in their territorial invincibility, a myth which US strategists called "benign isolation". Apart from Soviet nuclear missiles - now quietly rusting away - few other nations on Earth could hit at continental US and fewer still had any cause to do so.
Wars happened in other countries, and US governments sometimes had to decide whether to become involved or not. The choice, however, was always Washington's, and usually on its own terms.
This American myth died in the rubble of the Twin Towers in New York a year ago today: the threat of sudden death at the hands of enemies is now part of the American psyche. And the fact that destruction can come suddenly, perpetrated by people difficult to identify and seemingly impervious to reason, is now accepted as fact by every ordinary American citizen.
Europeans are still struggling to understand the sheer enormity of this psychological transformation across the Atlantic. Living in close proximity in relatively small countries, the Europeans have long grown accustomed to such risks.
Europe's preoccupation since the end of the second World War has therefore been to limit these dangers, rather than eliminate them altogether. This was accomplished by reducing the importance of the nation-state, while increasing the role of international or regional co-operation institutions.
The outcome is a continent which instinctively believes that military force is the last option to be used when all other diplomatic and economic measures have failed. But the US response to its current vulnerability has been precisely the opposite.
None of this was obvious immediately after September 11th. The atrocities were so horrendous that Europe's first response was to swing behind the US. And Washington initially surprised the Europeans by biding its time, building up a coalition of forces for its war in Afghanistan.
Yet the cracks across the Atlantic soon reappeared and they have widened ever since. The US administration has elaborated a host of new policies, with the explicit purpose of using military force as a first, rather than last, option.
The growth in US military expenditure is staggering: the Pentagon's current budget is equal to the combined spending of all the next 15 top military nations put together; the US accounts for half of the entire world's defence expenditure. And, crucially, the US is responsible for no less than 70 per cent of all the world's military research and development.
It is at best useless and at worst counterproductive for the Europeans to dismiss these moves as just the misguided policies of an unruly Texan sheriff, eager to shoot from the hip. For the divide is much more profound.
The Europeans instinctively wish to manage risk; the US still strives to eliminate its vulnerabilities altogether.
The Europeans believe that their nation-states have failed to solve their problems; the US asserts that the nation-state is the starting point for any solution.
The Europeans underestimated the effectiveness of military power; the US probably overestimates what sheer military force can achieve.
For relatively small European countries international institutions are a necessity; for the world's only superpower, such institutions are a luxury, to be used when necessary and discarded when inconvenient. The current debate over Iraq is merely a manifestation of this deeper divide, and it is unlikely to disappear for decades to come.
Beyond Europe, the strategic situation of almost any country around the world has changed during the last year. Having been merely a "partner", Russia is now an active ally of the US. President Vladimir Putin's response has finally dispelled the last lingering doubts which Washington had about this successor to the communist Soviet Union.
The scope of this alliance is now being expanded to the management of oil prices around the world, and joint action against weapons of mass destruction. There is no doubt that Russia has been a significant winner during the last year. And, conversely, there is little doubt that China has been a strategic loser.
Pakistan, China's old ally, is now a trusted partner of the US. American troops are in Central Asia as well as the Pacific, virtually encircling China from all directions. Furthermore, a host of other Asian countries - India, Singapore, Malaysia, Thailand, Indonesia, the Philippines - have either rekindled or established military links with Washington.
In short, an old superpower has been embraced, while China, a budding future major power, has been temporarily eclipsed. Meanwhile, Europe's own common foreign and security policy efforts have simply been ignored: the only major security event later this year will be NATO enlargement to the countries of eastern Europe, a project managed and mandated by the US.
And, behind the scenes, more subtle changes remain just as important. Support for Israel in the US is now widespread, not only among various ethnic lobbies which were traditionally grouped around the Democratic Party, but is particularly strong with the Christian fundamentalist right-wing organisations, which have a hold over the Republicans.
And disdain for Saudi Arabia, the country which has claimed to be a chief US ally while exporting a boorish, narrow-minded interpretation of Islam around the world, is now common in Washington.
This does not mean that the US cannot implement a coherent policy in the Middle East. But it does imply that President Bush's options in dealing with the Palestinian-Israeli conflict remain severely circumscribed.
And, in the long term, it must mean that the US would look for other regional key allies, beyond the desert monarchy of Saudi Arabia. One of the unspoken assumptions behind the determination to overthrow Saddam Hussein in Iraq is precisely the search for new Arab regimes which could be more democratic and pro-Western, but not dependent on Islamic fundamentalism for their legitimacy at the same time.
Whether this US strategy works or not, Saudi Arabia's importance for Washington seems destined to decline.
In essence, therefore, the kind of profound strategic changes which would have usually taken decades to become obvious have now happened in less than a year. A Japanese admiral, who was responsible for the attack on Pearl Harbour in 1941, later remarked ruefully that he had awakened a giant. If he can indulge in any thinking while hiding from the Americans, Osama Bin Laden should come to the same conclusion.
Jonathan Eyal is Director of Studies at the Royal United Services Institute in London