Nineteen ninety-five was an active year for terrorists in America: On April 19th, the federal building in Oklahoma City was bombed. Among the 167 people killed, 19 were children. On September 19th, a treatise appeared in the Washington Post written by a terrorist known as the Unabomber. He had threatened to kill more people if the paper refused to publish his manifesto. The following month, Sheik Omar Abdel Rahman and several of his followers were convicted of plotting to blow up the World Trade Center and several other New York landmarks. Fear reached as far west as Arizona, where someone removed 29 spikes from a train track and caused the derailment of an Amtrak train, an event that occurred within days of the Rahman verdict.

“A line has been crossed,” writes Los Angeles Times reporter David Wise. “We have become a vulnerable...