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Which US extremist groups have been responsible for the most violence since 2010?
Executive Summary
Since 2010, the preponderance of lethal and high‑profile violent incidents attributed to U.S. extremists have been carried out by racially or ethnically motivated violent extremists (RMVEs)—principally white‑supremacist and neo‑Nazi networks—and by anti‑government/anti‑authority violent extremists, including militia and “accelerationist” cells. Multiple U.S. government reviews and independent trackers conclude these two right‑of‑center threat categories account for the majority of incidents and deaths, with firearms as the dominant weapon [1] [2] [3].
1. Why two right‑wing threat categories dominate the casualty counts
Government reviews cataloging incidents from 2010–2021 show RMVEs and anti‑government extremists together account for the largest share of recorded attacks and deaths. The GAO counted 231 domestic‑terrorism incidents in that period, with RMVEs responsible for 80 incidents (35%) and anti‑government actors 73 incidents (32%), and RMVEs causing about 65% of the recorded deaths [1]. DHS and FBI strategic assessments for 2020–2021 likewise identify white‑supremacist groups and militia‑style anti‑state movements as the most lethal threat categories in the contemporary domestic‑terrorism picture [2]. These independent government tallies converge on the same conclusion: race‑based and anti‑authority right‑wing actors have been the most violent since 2010 [1] [2].
2. Independent trackers and academic reviewers reinforce the pattern
Academic and NGO trackers mirror the government narrative. The George Washington University trackers, Southern Poverty Law Center summaries, and European Parliament briefings all report that right‑wing, racially motivated extremists outpaced other ideologies in both incident counts and fatalities across the 2010s and early 2020s [3] [4] [5]. Independent analyses place roughly three‑quarters of domestic‑terrorism deaths since 2001 in right‑wing categories, a pattern that persists when isolating 2010–2021 data and when accounting for major single‑event casualties like mass shootings tied to white‑supremacist motives [6] [3]. The convergence between government datasets and independent monitors strengthens confidence in this assessment despite methodological differences.
3. Which specific groups have been repeatedly implicated in lethal plots
Investigations and prosecutions over the period highlight recurring organizational names: Atomwaffen Division, The Base, and other neo‑Nazi cells linked to murders and conspiracies; Boogaloo networks and militia affiliates implicated in plots against public officials and police; and conspiratorial anti‑government cells involved in the January 6 Capitol attack with spillover violence [2] [1]. Prosecutors and watchdogs also documented violence and plots tied to small, decentralized accelerationist cells whose networks spanned online forums and encrypted apps [2]. While the landscape includes many unstructured actors rather than formal hierarchies, these named groups and network types appear repeatedly in the government and academic record [2] [3].
4. The tools of violence and the human toll: firearms as the primary instrument
Across documented incidents from 2010–2021, firearms were the most common weapon and produced the majority of deaths, with reports noting 132 of 145 deaths in GAO’s dataset resulted from guns [1]. RMVEs accounted for the lion’s share of fatalities, amplifying the human toll of racially motivated attacks in public spaces, houses of worship, and workplaces [1] [5]. Government strategic assessments and academic trackers also note that perpetrators frequently blended ideological narratives of white supremacy or anti‑state doctrine with accessible weapons and lone‑actor operational models, producing high‑casualty incidents that shape the overall statistics [2] [3].
5. Caveats, data limits, and competing narratives to watch
Counting incidents across a decade and more involves methodological choices: definitions of “domestic terrorism,” classification of motive, inclusion of single‑issue actors, and reliance on open‑source versus classified data. The GAO and DHS/FBI reports cover 2010–2021 and use defined threat categories, but they do not list every individual responsible actor across all years; NGOs may include a broader set of incidents or use different inclusion rules [1] [7] [4]. Political actors and advocacy groups sometimes emphasize particular subsets—e.g., SPLC highlighting white‑supremacist organizing, or some law‑enforcement advocates focusing on militia threats—to advance policy priorities; readers should recognize these agenda‑driven emphases even where the underlying incident counts are consistent [4] [6].
6. Recent trends and what to watch next
Through the early 2020s the data show a steady dominance of right‑wing, race‑based and anti‑government violence in both incidents and fatalities, but analysts note evolving dynamics: decentralized lone‑actor threats, cross‑pollination between extremist networks, and episodic increases tied to political events [3] [2]. Ongoing monitoring by government agencies and academic trackers remains critical because small numbers of actors can produce disproportionate casualties, and shifts in online radicalization or weapon access could change the balance of violence in future years [2] [3]. Continue to rely on updated GAO, DHS/FBI, and independent tracker reports for the latest incident‑level breakdowns [1] [3].