The September 11, 2001 attacks on the World Trade Center in New York and Pentagon outside Washington, DC produced a profound sense of vulnerability within the US. To US government leaders, the evidence was now irrefutable that inflicting widespread death and destruction in the US had become key terrorist objectives, that terrorists would run high risks to implement these goals, and that the physical reach of these “new terrorists” was limited only by their ingenuity. They promised a future in which airliners loaded with fuel were transformed into firebombs, municipal water systems were poisoned, biological plagues were released on an unsuspecting population, and crude radioactive devices or nuclear bombs were exploded in populated areas.