Apparent intended lethality: Toward a model of intent to harm in terrorist bomb attacks

Abstract

This article sets out the concept of Apparent Intended Lethality (AIL) with respect to terrorist bomb attacks and explores its measurement through objective behavioral indices. AIL is assessed for 120 bomb attacks carried out by animal rights and anti-abortion extremists in the United States. A wide range of AIL is observed, ranging from hoax attacks to highly lethal attacks. Multidimensional Scalogram Analysis (MSA) reveals that single-issue terrorist bombers' intended lethality can be modeled according to three independent dimensions: device strategy, targeting, and pre-event warnings. This model can be used to measure AIL for an individual terrorist attack or an entire terrorist campaign, and can identify cumulative and compensatory lethality strategies. Many have noted the difficulty of assessing terrorist motivations; AIL provides an empirically based assessment of a key facet of terrorist intentions.

Keywords::

• terrorism
• extremism
• bomb attack
• single-issue terrorism
• Animal Liberation Front
• Anti-Abortion
• lethality

Acknowledgements

Support for this research was provided by the Department of Homeland Security, Human Factors/Behavioral Science Division, through the National Consortium for the Study of Terrorism and Responses to Terrorism (START). Any opinions, findings, and conclusions or recommendations in this document are those of the authors and do not necessarily reflect views of the Department of Homeland Security.

The authors are grateful to Allison Smith and Kevin Spence for their helpful comments on an earlier draft.