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Terror From Within: Examining U.S. Nationals Arrested since 9/11

Extremism in North America / Research and Visualization

In this detailed analysis, ISVG analyst Alana Penza takes a look at U.S. citizens who have been arrested on terrorism charges since September 11, 2001.


Since the terrorist attacks of 9/11, there has been a substantial increase in the number of homegrown terrorist threats; some homegrown militants have been successful in their attacks, such as Major Nidal Hasan, while others have been apprehended by federal authorities before the attacks could come to fruition (e.g. the “Fort Dix Six”, Mohamad Osman Mohamud).

In order to better understand the types of individuals involved with homegrown threats in the United States, the profiles of 162 United States persons were analyzed. In this analysis, a U.S. person was defined as anyone who is a natural-born citizen, naturalized citizen or permanent resident of the United States. Of the naturalized or permanent residents, which made up 47% of all cases, a large number of individuals came from Pakistan, Somalia, or Jordan.

The following map illustrates the countries of origin for naturalized U.S. citizens and permanent residents arrested on terrorism charges post-9/11:

*In all graphics the Serbian representation is from Kosovo.

Looking at Somalia’s history provides some clues as to why such a high number of individuals in the study came from Somalia: the country endured civil war in the 1990s and has failed to have a strong, structured government since. In 2006, international forces—including the Ethiopian army—invaded the country with the support of the United States. Parts of the Somali government were forced out of the capital, including an armed wing known as Al Shabaab[1].

Refusing to acknowledge the legitimacy of the government that took over following the invasion, Al Shabaab emerged as a terrorist organization and displayed that it was a threat to the Western world by announcing that it intended to overthrow the government trying to control Somalia and would impose its own version of Sharia law[2]. Somali-born individuals in the study were reported to have been arrested for providing financial support to the group or for recruiting others to fight in Somalia.

While Al Shabaab was not the only group represented in the study, a majority of individuals were charged with providing material support to terrorists in the form of training with terrorist organizations, engaging in conflict against the United States, or conspiring with an organization to attack unnamed targets.

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Though the ability of individuals or groups to carry out large-scale attacks in the United States has decreased, as evident in the arrests of the plotters, the threat to the United States homeland still remains. The analysis of the 162 individuals is merely a glimpse into the threats that have developed in the wake of the terrorist attacks of September 11, 2011.


[1] Somaiya, R. (2010, July 12). Who is Al-Shabab? Newsweek. Retrieved from http://www.newsweek.com/2010/07/12/the-rise-of-al-shabab.html



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