Al-Qaʿida’s attacks on September 11, 2001, were likely the most cost-effective use of military force in history. Conducted at the grand expense of several hundred thousand dollars, the attacks and the American overreaction cost the US Treasury some seven trillion dollars, and counting, in addition to the horrific loss of civilian and military lives on that tragic day. They did not, however, accomplish al-Qaʿida’s strategic objective of separating America from its allies in the Middle East, and al-Qaʿida was gravely damaged in the aftermath of the attacks even as the American efforts to remake Iraq and Afghanistan foundered.
Were the trillions of dollars America spent in the wake of al-Qaʿida’s catastrophically successful masterstroke a smart investment in the security of the American people? More briefly, does counter-terrorism work? Richard English, of Queen’s University Belfast, answers with a qualified “sometimes” in his short new book, already in press by the time...