From an Atlantic article by a counterterrorism guru
... This 'war' will never be over, unlike the Civil War, the Vietnam War, or even the current war in Iraq. There will always be a threat that someone will blow up an airplane or a building or a container ship. Technology has changed the balance of power; it is easier for even a handful of people to threaten a community than it is for the community to defend itself. But while we have to live in danger, we don't have to live in fear...I wrote this in October of 2001:
Over the past century technology has increased destructive power more than it has increased defensive capabilities. Technology, including communication networks and knowledge distribution, has brought to individuals and small groups (micro-powers) the capabilities once limited to nation states; the cost of acquiring and deploying nuclear and particularly biological weapons has decreased substantially. It has increased the harm potential of individuals and small groups. I sometimes call this the AIM problem, a pseudo-acronym for Affordable, Anonymous Instruments of Mass Murder. Our technologies are lowering the cost of the havoc, and the new weapons can be deployed anonymously. Anonymity means invulnerability. We cannot be anonymous, so we are are at an enormous disadvantage -- eventually contending against an invulnerable opponent with irresistible weapons.