The FBI is supposed to be the nation’s police force but the bureau’s primary mission is secret intelligence. In Tim Weiner’s new book “Enemies” the author tells the story of how presidents have used the FBI as the most important intelligence force in American history.

Using extensive research into previously unavailable materials, Weiner looks at how the FBI has fought against anyone it deemed subversive, including terrorists, spies, and sometimes even American presidents. “Enemies” examines how the FBI’s secret intelligence and surveillance techniques have long created tension between the need to protect national security and the infringement on civil liberties.

Through a detailed examination of the FBI’s notorious director J. Edgar Hoover, the author, whose work on the Pentagon and the CIA won him the Pulitzer Prize and the National Book Award, reveals how the historic tug between surveillance and civil rights strained (and still strains) the very fabric of a free republic.

Is it worth it? Can we tolerate the FBI’s secret surveillance techniques in order to achieve national security?

Guest:

Tim Weiner, author of "Enemies: A History of the FBI" (Random House)