Why Have We Not Been Attacked Again? Competing and Complementary Hypotheses For Homeland Attack Frequency   [open pdf - 2MB]

"This report examines a number of competing and complementary hypotheses that seek to explain the non-occurrence of a large-scale terrorist attack on the U.S. homeland since 9/11. While the study's title seems implicitly to ask why al-Qaeda has not succeeded in a second homeland attack, the analysis also considers groups within the broader radical Islamist movement as well as non-religious groups and lone individuals. Before examining the competing hypotheses, several terms and assumptions must be clarified, each of which is linked to the way that the report, as well as the individual theories, has posed the basic question: Why has the United States not been attacked since 9/11? Clearly a number of terrorist plots against the U.S. homeland have been identified since 9/11, a fact that confirms that the United States has been attacked again. However, the hypotheses put forward in this report should be read as seeking to explain the lack of a successful attack on the homeland. At the same time, the existence of attempted or thwarted attacks constitutes important evidence that bears upon the credibility of many of the hypotheses. In seeking to explain the non-occurrence of another attack, the report focuses predominantly on 'large-scale' operations rather than 'small-scale' attacks, especially in the analysis of terrorist capabilities. However, no rigorous attempt is made to define these terms precisely given that any boundaries are likely to be somewhat arbitrary as well as of uncertain utility." Note: This document has been added to the Homeland Security Digital Library in agreement with the Project on Advanced Systems and Concepts for Countering WMD (PASCC) as part of the PASCC collection. Permission to download and/or retrieve this resource has been obtained through PASCC.

Report Number:
ASCO Report Number 2008 007
Public Domain. Downloaded or retrieved via external web link as part of the PASCC collection.
Retrieved From:
Heritage Foundation: http://www.heritage.org/
Media Type:
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Listed on August 13, 2008 [Critical Releases]