As shocking as the attacks of 9/11 were, we have been too quick to view the post-9/11 struggle against terrorism as entirely new and unprecedented. Without denying certain novel aspects of Al Qaeda and its affiliates, the -newness- of its purpose and methods has been overemphasized. Many aspects of contemporary terrorism bear a striking resemblance to past movements. Others represent the culmination of trends evolving over decades. Even seemingly novel characteristics of terrorist methods may be more the outcome of earlier developments than a truly new phenomenon. The increased lethality of...