According to a review in Times Higher Education that described '' Age of Lone Wolf Terrorism '' as an " genuinely indispensable study of today ’s steadily increasing terrorist threat , " the book 's " pivotal contention " that the radicalization of lone wolf terrorists exhibits discernible patterns that include “ the integration of personal and political grievances ; an affinity with online sympathizers and/or extremist groups , " and " triggering events that , oftentimes , cause a dramatic change in behavior ” . Hamm and Spaaij constructed a database funded by the United States Department of Justice in which they identified 124 instances of lone wolf terrorist attacks in the United States between 1940 and 2016 ; the list includes " about " 30 planned attacks that are known not to have been carrier out , or that have been identified as FBI sting operations , or as hoaxes . Hamm and Spaaij defined lone wolf terrorism narrowly ; they required an attacker to be politically motivated , this excluded , for example , mass shooters such as Adam Lanza , whose motive appeared to be entirely personal . And they had to have acted entirely alone , excluding cases like the 2015 San Bernardino attack carried out by a married couple , and the Boston Marathon bombing , carried out by a pair of brothers . Kris Millett ( 2017 ) : Hamm & Spaaij ’s The Age of Lone Wolf Terrorism and the prospect of a heterodox terrorism studies ( book review ) , Critical Studies on Terrorism , DOI : 10.1080 / 17539153.2017.1384154 . The tightness of this definition was widely criticized . Hamm and Spaaij use data they compiled , and examinations of the lone wolf phenomenon by other researches to reach a series of conclusions
Boston Marathon bombing
Boston Marathon bombing
Age of Lone Wolf Terrorism