Which right-wing extremist groups have been responsible for the most violent attacks in the USA between 2015 and 2024?

1. Summary of the results

Right-wing extremist actors are identified in multiple analyses as the principal source of fatal and frequent domestic terrorist violence in the United States across the period in question. Several independent summaries in the provided analyses note that attacks attributed to right-wing extremists accounted for the vast majority of fatalities in U.S. domestic terrorism since 2001 and remained dominant between 2015 and 2024 ^{[1] [2]}. The datasets cited indicate higher counts of incidents and deaths tied to right-wing motivations compared with left-wing motivated violence, with some studies quantifying right-wing responsibility as roughly 75–80% of domestic terrorism deaths ^{[1] [3]}.

Analysts also emphasize incident-rate differences: right-wing incidents occurred more frequently annually than left-wing incidents through the recent decade, often averaging around two to three dozen incidents per year in some characterizations versus a much smaller number for the left ^[4]. High-profile examples frequently invoked to illustrate the lethality of right-wing attacks include shootings targeting religious and minority communities, demonstrating both the frequency and severe fatal outcomes associated with these actors ^{[3] [1]}. These summaries present a consistent pattern across the supplied analyses attributing the majority of U.S. domestic terrorism fatalities in the 2015–2024 window to right-wing extremist groups.

Several of the provided analyses additionally note temporal fluctuations within that broader pattern: while right-wing violence dominated the overall decade, shorter-term shifts were observed, including a reported decline in right-wing incidents in the first half of 2025 and a small uptick in left-wing incidents during that interval ^[4]. These caveats indicate that dominance by right-wing actors is not necessarily uniform year-to-year, and that specific yearly or monthly trends can diverge from the multi-year aggregate. The analyses collectively warn against assuming static trends without attention to the timeframe and methodological choices used to count incidents and fatalities ^{[3] [2]}.

2. Missing context/alternative viewpoints

The supplied analyses focus on aggregate counts of incidents and fatalities but omit important methodological context that affects interpretation, such as how incidents are classified, criteria for “terrorism,” and whether lone-actor cases are grouped with organized groups ^{[5] [3]}. Alternative viewpoints emphasize that different databases and researchers use diverging definitions—some count any politically motivated killing as terrorism, others require demonstrable organizational ties. Without the underlying datasets and coding rules, percentages like “75–80% of deaths” can obscure classification choices that materially change tallies ^{[3] [2]}.

Another missing context is the role of non-group-affiliated actors (lone actors or followers of loosely organized online movements) versus named extremist groups. The provided analyses attribute most violence to “right-wing extremists” broadly, but they do not consistently separate attacks carried out by formal groups (e.g., organized militias) from those by self-radicalized individuals citing right-wing ideologies. That distinction matters for policy responses and prevention strategies, because interventions differ between dismantling organized networks and addressing online radicalization pathways ^{[1] [4]}. Omitted are disaggregations by target type, geographic concentration, and weapon type, which shape the operational risk picture ^[3].

Sources also downplay or omit countervailing measures and legal responses that can influence incident counts, such as improved intelligence operations, prosecutions, or community interventions implemented during 2015–2024. If prevention efforts intensified at different times or places, annual incident counts could reflect enforcement dynamics rather than raw changes in extremist intent or capability. Additionally, the supplied analyses briefly note a 2025 decline in right-wing incidents, but they do not fully explore whether that trend originated from enforcement, reporting changes, or genuine reductions in violence, leaving open alternative explanations that would alter interpretation of the 2015–2024 baseline ^[4].

3. Potential misinformation/bias in the original statement

Framing the question as “Which right-wing extremist groups have been responsible for the most violent attacks” can unintentionally conflate ideology with organizational culpability, benefiting narratives that emphasize certain threat types over others. The supplied analyses consistently highlight right-wing actors as predominant, which may reflect selection bias toward datasets that categorize many lone-actor incidents as “right-wing extremist” without distinguishing organizational affiliation ^{[5] [1]}. Actors or institutions advocating for increased counter-extremism resources might benefit from emphasizing the scale of right-wing violence to justify policy or funding priorities ^[2].

Conversely, political actors seeking to minimize right-wing violence could point to short-term fluctuations (e.g., the reported 2025 decline) or differences in definitional practices to argue that the dominance of right-wing violence is overstated. Such actors may highlight methodological caveats to deflect accountability for persistent threats. The analyses themselves note such temporal and definitional nuances, suggesting that the claim benefits groups on both sides of the debate depending on which aspects (aggregate fatalities versus year-to-year trends or organizational vs. lone actors) are emphasized ^{[4] [3]}.

Finally, absent granular attribution in the provided analyses, naming specific groups as responsible for “the most violent attacks” risks propagating incomplete or misleading conclusions; policy and public discourse benefit from disaggregated data—distinguishing formal organizations, ad hoc networks, and lone actors—so responses can be proportionate and evidence-based. The supplied sources collectively point to right-wing extremists as the dominant vector of domestic terrorism fatalities in the period, but they simultaneously underscore the need for transparent methodology and disaggregation to avoid mischaracterizations that could be exploited for partisan aims ^{[3] [4]}.