Tomorrow's New York Times magazine has a huge article on this (requires free subscription):

http://www.nytimes.com/2003/02/23/ma...3FORTRESS.html

Excerpt:

Fortress America

By MATTHEW BRZEZINSKI

In the last several weeks, as preparations for the war against Iraq have heated up, it has begun to sink in that this will be a different conflict from what we have seen before -- that there may, in fact, be two fronts, one far away on the ground in the Middle East, the other right here at home. For the first time in history, it seems plausible that an enemy might mount a sustained attack on the United States, using weapons of terrorism. The term "soft targets," which refers to everyday places like offices, shopping malls, restaurants and hotels, is now casually dropped into conversation, the way military planners talk about "collateral damage."

Earlier this month, the federal government raised the official terrorism alert level and advised Americans to prepare a "disaster supply kit," including duct tape to seal windows against airborne toxins. Members of Congress organized news conferences to demand that passenger jets be outfitted with missile-avoidance systems. In major public areas of cities, the police presence has been especially conspicuous, with weapons ostentatiously displayed. Whatever the details, the message was the same: war is on the way here.

The impossible questions begin with where, what and how, and end with what to do about it.