Fact check: Which domestic terrorism groups have been responsible for the most violent attacks in the US since 2020?

1. Why multiple datasets point to right-wing violence dominating recent domestic terrorism deaths

Independent research from 2020 and more recent analysis in 2025 both indicate that far-right and white supremacist actors are responsible for the greatest share of deadly domestic terrorist attacks in the United States. A 2020 CSIS dataset found white supremacists and ideologically aligned extremists conducted two-thirds of terrorist plots and attacks that year, noting they outpaced other perpetrator types ^{[1] [5]}. Subsequent government reporting in 2025 and a September 2025 study reinforced that right-wing attacks are more frequent and have produced the majority of fatalities, estimating roughly 75–80% of domestic terrorism deaths since 2001 resulted from right-wing actors—a continuation of patterns observed since 2020 ^{[3] [4]}.

2. What government threat assessments changed or confirmed after the 2020 surge

Federal threat assessments in 2020 and 2025 both flagged domestic violent extremism—particularly white supremacist violent extremists—as a significant homeland threat, with the latter assessing that the terrorism threat environment would remain high due to sociopolitical drivers and post-election dynamics ^{[2] [4]}. The 2020 Homeland Threat Assessment highlighted exploitation of protests and the risk of destruction and violence by domestic violent extremists ^[2]. The 2025 DHS judgment updates this by noting a sustained high-threat environment driven by multiple factors, and it emphasizes that right-wing violence is currently more frequent and lethal than left-wing violence, reflecting continuity and escalation in official concern ^[4].

3. How academic and NGO trackers characterized the landscape in 2020–2021

Academic and non-governmental trackers in 2020–2021 emphasized the prominence of white supremacist groups and unaffiliated actors, naming entities such as the National Socialist Movement, Atomwaffen Division, Proud Boys, and the Boogaloo movement among active violent actors, and noting many attacks were carried out by unaffiliated individuals inspired by these networks ^{[6] [1]}. These sources reported substantial increases in incidents and plots between 2013 and 2021, illustrating a broader trend of escalation that set the baseline for the subsequent threat environment described in later government reports ^{[7] [5]}.

4. Data limitations and why single-source conclusions are risky

The available analyses note important data gaps and temporal limitations: some summaries rely on datasets ending in 2021 while later studies extend conclusions into 2025, producing potential comparability issues ^{[6] [3]}. The 2024 year-in-hate assessment documents a large number of hate and antigovernment groups but does not singularly identify which groups caused the most violence since 2020, underscoring that counts of groups do not map directly to counts of violent attacks ^[8]. Diverse methodologies—source selection, incident definitions, and fatality attribution—mean single-source claims can misrepresent trends unless cross-validated ^[7].

5. Alternative perspectives: the role of left-wing and other actors

While the dominant conclusion across sources points to right-wing predominance, trackers also record nontrivial participation by anarchists, anti-fascists, and left-wing actors in certain years and protests; a 2020 CSIS analysis assigned about 20% of plots and attacks that year to anarchists and anti-fascists, showing that left-wing violence has localized and temporal significance ^[1]. Earlier commentary cautioned against two misleading narratives—portraying terrorists only as Muslims or only as non-white—warning that such biases could create security blind spots and distort policy focus ^[9]. These perspectives emphasize the need to account for multiple perpetrator types even as right-wing actors predominate.

6. What policymakers and researchers emphasize for next steps

Across government and NGO reporting, there is consistent emphasis on improving information sharing, strategic planning, and cross-sector collaboration to counter rising domestic terrorism, reflecting both the increased volume of groups documented in 2024 and the uptick in incidents through 2021 and into the mid-2020s ^{[7] [8] [4]}. Reports call for nuanced threat prioritization—addressing the most lethal and frequent actors while avoiding profiling-based blind spots—because mitigation requires targeted interventions that reflect the evolving actor landscape described by multiple datasets ^{[7] [4]}.

7. Bottom line: who has been most responsible for violent attacks since 2020?

Synthesizing government assessments, academic datasets, and NGO reports from 2020 through 2025 yields a clear convergence: right-wing and white supremacist extremists have been responsible for the bulk of violent domestic terrorist attacks and deaths since 2020, with anarchist/anti-fascist actors and other categories contributing to a smaller share of incidents in certain periods. This conclusion rests on multiple, independently produced datasets and official threat assessments, though analysts note methodological differences and urge continued, multi-source monitoring to refine attribution over time ^{[1] [3] [6]}.