Former CIA analyst and retired University of California professor Chalmers Johnson examines the concept of blowback — the unintended costs and consequences of American imperialism and how it is connected to the Sept. 11 attacks.

Since September 2001, the United States has “undergone a transformation from republic to empire that may well prove irreversible.”

This is what scholar and author Chalmers Johnson writes in his new book The Sorrows of Empire: Militarism, Secrecy and the End of the Republic. The book discusses the roots of American militarism, the rise and extent of the military-industrial complex, and the close ties between arms industry executives and high-level government officials.

• Chalmers Johnson, leading scholar of Asia and US-Asian relations, his previous book is Blowback: The Costs and Consequences of American Empire.