It came out of the blue on a crystalline morning, bringing a carefree American summer to a shattering conclusion. Turning passenger jets into flying bombs, Osama bin Laden's acolytes struck with a chilling genius.
The planes turned the might of New York's commercial totems - the World Trade Centre twin towers - in on themselves, creating an avalanche of steel and rubble that killed 2,481 people. Another slammed into the Pentagon in Washington, destroying the sense of security and comfortable isolation that only unprecedented military superiority can bring.
One year on, it is possible to argue that bin Laden has turned America's might against itself as well. Another winter approaches full of fear, uncertainty and international tension, laced with the prospect of a second conflict in Iraq and the ongoing mystery surrounding bin Laden and his network.
An early international coalition is teetering under the weight of months of unashamedly unilateralist 'with us or against us' rhetoric from US President George W. Bush and his Republican team. Even some of America's firmest allies are questioning the future. An America that is prepared and able to stand alone, if need be, remains paradoxically isolated and vulnerable.
At home in the self-proclaimed 'Land of the Free', some of America's most cherished freedoms lie under attack in the name of Mr Bush's 'new war'. Fully armed jet fighters are often seen swooping low over America's big cities. Pockets of immigrants fear the midnight knock at the door, secret detention and summary deportation. America's extensive intelligence machine has been given new powers akin to excesses from some of its darkest periods. FBI agents, for example, are free to monitor church congregations.
At times, domestic debate has seemed stifled beneath a welter of patriotism, sometimes being turned on its head. In the aftermath of September 11, arch-liberal lawyers have publicly demanded government-sanctioned torture, Quakers have urged war and Christian preachers the use of tactical nuclear weapons.
