Just a few days before Christmas, 2003, just as this manuscript was to be sent to the editor, the Bush administration and the Department of Homeland Security raised the threat level for the fourth time since 9/11 to Orange-meaning increased security for travelers, ports, key elements of the U.S. infrastructure, and major cities. People seemed to take the warning of an increased possibility of a terrorist attack on the United States in stride. There was no panic, and most people seemed to go about their business as usual. Was al Qaeda really at work to strike at the United States? The increase in the alert level was based on a high volume of terrorist communication around the world, even though the terrorists knew that U.S. intelligence was listening to what they were saying and writing.
Most observers expect another terrorist strike within the United States, but no one knows where the terrorists will hit us or when. While intelligence seems good enough to detect an increased threat level in general, the system has not yet perfected the sophisticated tools needed to give specific warning. How such tools might be developed is one of the key subjects of this book.
There seemed to be no good reason to delay publication of this book. To wait for the terrorists to strike again or for the other issues and decisions anticipated in the months to come to be resolved may have delayed publication indefinitely.
In some respects, if there is another terrorist strike, it will be a test of the systems that have been put in place since 9/11—another subject of this