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Database Spotlight: Update on Profiles of Perpetrators of Terrorism in the US

Dataset provides unmatched insights into the characteristics of terrorist groups that have carried out attacks on U.S. soil
The National Consortium for the Study of Terrorism and Responses to Terrorism (START) recently updated its Profiles of Perpetrators of Terrorism in the United States (PPT-US) dataset, which provides detailed information on organizations known to have engaged in terrorist activity against targets on United States soil between 1970 and 2011.
Built by a small team of START research assistants directed by Global Terrorism Database (GTD) Manager Erin Miller and START investigator Kathleen Smarick, the dataset allows researchers and analysts to examine the characteristics of terrorist groups that carried out attacks in the United States. The PPT-US provides researchers with descriptive narratives on the history and philosophy of each organization, as well as information on variables such as ideology, structure and involvement in activities other than terrorism.
Upon reviewing newly released data from START's GTD and other sources, the research team updated the profiles of 31 terrorist groups in the PPT-US, added seven groups and removed three groups that did not satisfy inclusion criteria.
As part of the Integrated U.S. Security Database (IUSSD) project, which is funded by the U.S. Department of Homeland Security Science and Technology Directorate's Resilient Systems Division, PPT-US provides researchers and analysts with group-level contextual information that complements data on terrorist activity and individual perpetrators from sources such as the American Terrorism Study, the GTD and the Extremist Crime Database.
Preliminary findings: 1970-2011
According to Miller, preliminary findings from the PPT-US database indicate there is no "profile" of organizations that target the U.S. homeland with terrorism. Rather, the groups that have attacked in the United States between 1970 and 2011 have widely varied ideologies, beliefs and goals.

Of the 147 terrorist groups that have conducted at least one attack in the United States between 1970 and 2011:

  • 56 percent carried out attacks for less than one year
  • 85 percent had headquarters in the United States
  • 54 percent also engaged in non-violent political activities
  • 97 percent emerged before the year 2000

Between 1970 and 2011, 32 percent of the perpetrator groups were motivated by ethnonationalist/separatist agendas, 28 percent were motivated by single issues, such as animal rights or opposition to war, and seven percent were motivated by religious beliefs. In addition, 11 percent of the perpetrator groups were classified as extreme right-wing, and 22 percent were categorized as extreme left-wing.

Preliminary findings from PPT-US data between 1970 and 2011 also illustrate a distinct shift in the dominant ideologies of these terrorist groups over time, with the proportion of emerging ethnonationalist/separatist terrorist groups declining and the proportion of religious terrorist groups increasing. However, while terrorist groups with religious ideologies represent 40 percent of all emergent groups from 2000-2011 (two out of five), they only account for seven percent of groups over time.

Future directions

In the next phase of their PPT-US research, Miller and Smarick plan to examine relationships among many of the characteristics identified in the dataset, including whether there is a correlation between specific goals of a group and that group's duration, or between a group's ideology, its other political activities and the nature of the terrorist attacks it perpetrated. By providing the first structured, comparable dataset on groups that have engaged in terrorism against the U.S. homeland, the PPT-US helps advance the science of terrorism studies and serves as an valuable resource for counterterrorism researchers and analysts.