By National Academies of Sciences, Engineering, and Medicine.

Domestic and foreign violent extremist organizations, or terrorist groups, have caused a greater amount of harm with chemical agents than with biological or radiological weapons. The United States capacity and capability to identify, prevent, counter, and respond adequately to chemical threats is established by the strategies, policies, and laws enacted across multiple levels of government. While the number of chemical terrorism incidents has risen and fallen over time, there is no empirical or analytical indication that the threat is disappearing. This report comes at a time when the nation's highest-level strategies have shifted from focusing primarily on violent extremist organizations to focusing more on Great Power Competition. This shift in relative perceived threat and consequent prioritization will impact efforts against chemical terrorism, and in turn, affect funding priorities. Revised risk assessments are needed to reprioritize risks guided by new strategies, so that strategy-aligned budgets can be created. The report recommends weapons of mass destruction budgets be aligned with evolving priorities and incentivize activities that transition promising research to operations.

Washington, DC: The National Academies Press.2024, 186p. https://doi.org/10.17226/27159.

By Megan K. McBride, Kaia Haney, Michelle Strayer, and Jessica Stern

Despite the focus on suicide terrorism over the past 20 years—particularly by media outlets, policy-makers, and academics—scholarship regarding suicidality in domestic terrorism remains sparse. The post-9/11 research related to suicidality in terrorism has largely focused on the suicide terrorism of Islamist extremists. The research that touches on domestic terrorism, however, is both limited and inconclusive. Lankford, for example, has argued that suicidality is one of three key similarities between perpetrators of suicide terrorism and perpetrators of mass shootings. But a 2017 article by Freilich et al., whose research focused on far-right and jihadi attacks in the US, found that suicide attackers were no more likely than non-suicide attackers to have previously attempted suicide. By contrast, suicidality among those who carry out public shootings is well documented. Jillian Peterson and James Densley, leveraging The Violence Prevention Project’s (TVPP’s) Mass Shooter Database, found that 70 percent of the 197 individuals who committed mass shootings over the past 60 years either had a history of suicidality or intended to die carrying out their attack. Retrospective research by the US Secret Service on school shooters from 1974 to 2000 found that at least 78 percent had experienced suicidal thoughts or engaged in suicidal behavior before their attack. And an analysis leveraging the Columbia Mass Murder Database found that nearly half of all mass shooters died by suicide at the scene of their attack. Mass shootings, as Peterson and Densley have noted, may in fact be “crimes of despair.” We leveraged a new dataset—the Domestic Terrorism Offender Level Database (DTOLD)—to explore whether domestic terrorism attacks may also be crimes of despair. The database captures publicly available information (e.g., media reporting, court records) on the life histories of 320 individuals who carried out a non-Islamist terrorist attack in the United States between January 1, 2001, and December 31, 2020. Our data suggest that domestic terrorists in general may be more suicidal than the general population but significantly less suicidal than mass shooters except when domestic terrorists kill four or more people (notably, four is the number of deaths required for a shooting to meet the Federal Bureau of Investigation’s definition of a mass shooting). DTOLD contains three variables relevant to the question of suicidality: history of suicidality (including suicide attempts and suicidal ideation), intention to die while committing a terrorist attack, and death by suicide during or immediately after a terrorist attack. Collecting data on suicidality is difficult, but 19.3 percent (62) of the individuals in DTOLD have been coded positively for at least one of the three indicators of suicidality. This rate is notably higher than the rate calculated by the Substance Abuse and Mental Health Services Administration, which is 4.37 percent for men (89 percent of those in DTOLD are men). This rate is still lower, however, than TVPP’s rate of 70 percent among mass shooters.

Arlington, VA: CNA, 2024. 4p

By Megan K. McBride and Monique Jenkins

Within the public violence literature—that is, the literature on domestic terrorism, mass shootings, school shootings, and hate crimes, among others—leakage has been identified as a core warning behavior. Leakage occurs when a would be assailant communicates an intention to harm a target before committing an attack.1 This communication can vary in timing, level of detail, form, intentionality, and audience.2 Through such a communication, an individual might directly verbalize an intent to commit an act, make more subtle threats and innuendos, or share a plan via social media.3 Researchers have found relatively high levels of leakage associated with acts of public violence, including adolescents perpetrated mass murders,4 mass shootings,5 political and public figure assassinations,6 and domestic terrorism.7 For this reason, leakage—which often occurs in interactions online or with loved ones—can be an important warning sign. But leakage to family, friends, or acquaintances is not the only way to detect when an individual is intending to commit an act of public violence, and over the last decade, researchers have started to examine preattack contact with system stakeholders, such as law enforcement, mental health, and education professionals. For example, one study found that 40 percent* of violent extremists had engaged in a crime before their act of extremist violence.8 Another study reported differences in system contact for lone and group-affiliated actors among American far-right extremists who committed fatal attacks. Specifically, it found that 61.7 percent of lone actors, but just 51.1 percent of group-affiliated extremists had prior arrests.9 In addition, multiple case studies exploring the personal histories of small populations of violent extremists have included information on system contact.10 However, comprehensive research exploring previous contact between system stakeholders and individuals engaged in domestic terrorism is relatively scarce. We sought to advance understanding of what percentage of the violent extremist population could be “catchable” in the sense that an individual had been in previous contact with a system stakeholder (e.g., law enforcement, mental health provider) or had been reported to a system stakeholder (e.g., by a friend or loved one to whom they had intentionally or unintentionally leaked information). To explore this issue, we leveraged a new dataset: the Domestic Terrorism Offender Level Database (DTOLD). The database includes detailed information on the 320 non-Islamist individuals who carried out terrorist attacks in the United States between January 1, 2001, and December 31, 2020. Specifically, we sought to understand what percentage of this population was known to system stakeholders at some point before they perpetrated their attacks. 

Arlington VA: CNA, 2024. 4p

By  Lisa N. Sacco

The federal government defines domestic terrorism (DT) as ideologically driven crimes committed by individuals in the United States that are intended to intimidate or coerce a civilian population or influence the policy or conduct of a government. Federal definitions of DT are found in the USA PATRIOT Act (18 U.S.C. §2331), the Homeland Security Act (6 U.S.C. §101), and Title 28 of the Code of Federal Regulations (§0.85). Aside from the statutory and regulatory definitions of DT, the Federal Bureau of Investigation (FBI) has historically emphasized particular qualities inherent to the actors who engage in DT. According to the FBI, domestic terrorists are Americans who commit violence to achieve their goals that stem from domestic, extremist ideological influence and lack of foreign direction or influence. This conceptualization excludes ideologically driven crimes committed in the United States by individuals whose actions are directed or motivated by foreign groups. Analyst in Illicit Drugs and Crime Policy How the federal government defines conceptualizes and shapes the nation’s understanding of it as criminal conduct and as a policy issue. Domestic terrorists (and the crimes they commit) are labeled as such because their actions are directed against the civilian population and/or U.S. government within the boundaries of the United States. Like foreign terrorism, domestic terrorism involves ideologically driven criminal acts aimed at influencing the government or coercing the population. Unlike foreign terrorism, the federal government does not have a mechanism to formally charge an individual with DT, which sometimes makes it difficult (and occasionally controversial) to formally characterize someone as a domestic terrorist. Further, domestic terrorists may adhere to the ideologies of certain extremist movements or belong to hate or extremist groups, but unlike the formal process involved in designating foreign terrorist organizations, DT movements and groups are not officially labeled as such by the federal government, thereby making it difficult to categorize the threat presented by any group or movement as a DT threat. While some observers may look to terrorism-related incidents, investigations, and arrests to help understand the scope of the DT threat, these data are limited. DT incidents have a low occurrence rate but a high impact, and the federal government has a significant role in combatting the threat of DT. In 2021, the FBI and the Department of Homeland Security (DHS) issued the nation’s first national strategy for countering the DT threat. The strategy identifies DT threats to include potentially unlawful use or threats of force or violence in furtherance of ideological agendas from racially or ethnically motivated violent extremists, anti-government or anti-authority violent extremists (further broken down to include militia violent extremists, anarchist violent extremists, and sovereign citizen violent extremists), animal rights/environmental violent extremists, and abortion-related violent extremists. How the government defines and combats DT and extremism is complicated for many reasons. Believing in or expressing extremist ideals and/or vocalizing support for DT incidents are not violations of federal law. If an individual in the United States espouses extremist beliefs, such as anarchy or the superiority of the white race, that behavior is generally protected speech under the First Amendment. Expressions of these beliefs sometimes precede DT incidents, and in hindsight, some may question why these incidents could not be prevented. Crossing the line from First Amendment-protected activity, such as a peaceful protest, to DT-related violence can happen quickly; however, there is often little law enforcement can do in response to extremist but protected speech. Despite the statutory definition of DT in Title 18 of the U.S. Code, no federal criminal provision expressly prohibits “domestic terrorism.” While DT is defined in federal statute, the term domestic terrorist is not used to officially label any group (as it is with foreign terrorist organizations). However, federal law enforcement has referred (in some instances such as congressional testimony) to individuals as domestic terrorists and their crimes as DT. Going forward, Congress may consider any number of legislative options regarding the federal government’s approach to defining and confronting DT, including (1) enactment of a DT charging statute; (2) the utility and consequences of applying the DT label in federal policy; (3) allocation of additional, less, or equivalent appropriations to address DT; and (4) adjustments to DT data collection requirements for federal agencies.  

Washington DC: Congressional Research Service, 2023. 27p.