What are the primary ideologies associated with domestic terrorism in the United States?

1. Right‑wing and racially motivated violence: the longest‑running, data‑backed threat

Multiple analyses and datasets show that racially or ethnically motivated violent extremism — especially white supremacist and broader far‑right variants — has been a dominant category of domestic terrorist activity in the U.S.; CSIS reports that right‑wing actors, including white supremacists, anti‑government extremists, and "incel" subgroups, accounted for the majority of attacks and plots in long‑term datasets ^[2]. Government reporting and independent media summaries also indicate right‑wing extremist violence has produced a disproportionate share of fatalities in the post‑2001 era (PBS summarizes that right‑wing violence caused roughly 75–80% of domestic terrorism deaths since 2001) ^[4].

2. Anti‑government and partisan extremism: lone actors and small cells

Anti‑government ideologies — a subset of right‑wing extremism but often discussed separately — and partisan political violence have surged in recent years, with many attacks executed by lone actors or small cells rather than formal organizations; the U.S. intelligence community and CSIS note that lone‑wolf or small‑cell actors are increasingly likely to carry out attacks and that targeted attacks against government institutions rose sharply in recent cycles ^{[5] [1]}. CSIS also finds that partisan political motivations have driven a recent spike in attacks against government targets, nearly tripling some measures compared with earlier decades ^[5].

3. Salafi‑jihadism and foreign‑inspired violence: still present, often lethal

Although transnational jihadist groups like ISIS and al‑Qaeda have waxed and waned in influence, CSIS and other threat assessments continue to list Salafi‑jihadism as one of the ideologies motivating U.S. domestic attacks — sometimes through foreign‑inspired lone actors — and note that jihadist attacks, while fewer in number than some domestic categories, can be highly lethal when they occur ^{[1] [6]}. DHS and congressional overviews also remind readers the domestic threat picture includes foreign‑linked violent actors or sympathizers who adopt jihadist aims ^{[3] [7]}.

4. Left‑wing and protest‑related violence: rising from low baselines

Left‑wing or anti‑state violence remains a smaller portion of recorded domestic terrorism historically, but several reports note a rise in left‑wing incidents in recent years — often tied to demonstrations and protest dynamics — even as overall levels remain lower than right‑wing totals (CSIS notes left‑wing attacks increased from low levels and that attacks related to demonstrations rose in 2020–2021) ^{[8] [9]}. Analysts caution that part of the relative increase reflects declines in other categories and that trends can be volatile ^[8].

5. Other categories: single‑issue, nihilistic, and “other” motives

Beyond the major ideological families, government definitions and academic reviews include niche or nontraditional drivers such as eco‑extremism, extreme animal rights violence, nihilistic violent extremism, ethnonationalist actors, and criminal or apolitical violence mischaracterized as ideological; Congress’s CRS and DHS materials catalog these categories and how agencies classify incidents ^{[7] [3]}. CSIS coding of past incidents also places some events into an “other” bucket where motives don’t fit standard categories ^[2].

6. Definitions, data limits, and why comparisons vary

How agencies and researchers define “domestic terrorism” affects findings: the FBI and DHS use statutory and operational definitions that emphasize ideologically motivated violence, while academic datasets apply narrower or broader criteria; these methodological differences explain why counts and shares differ between CSIS, DHS, FBI, and media summaries ^{[7] [10]}. CSIS warns that lone actors are harder to detect and that group plots may be disrupted more often — biasing observable datasets toward completed lone‑actor attacks ^[5].

7. Policy context and competing narratives

Policy documents and political actors emphasize different threats for different ends: some government assessments and congressional offices stress foreign jihadist and antisemitic attacks amid global conflicts, while other analyses and independent researchers highlight long‑standing dominance of right‑wing and racially motivated terrorism; these competing emphases can reflect institutional priorities and political agendas ^{[3] [11] [4]}. Available sources do not mention any definitive single cause; instead they portray a plural threat environment where multiple ideologies spur violence ^{[1] [2]}.

Conclusion — what to take away

The record in available reporting points to three principal ideological drivers of U.S. domestic terrorism in recent years — right‑wing/racially motivated extremism (including anti‑government variants), partisan/political extremism, and Salafi‑jihadism — with secondary contributions from left‑wing and issue‑specific actors; interpretation of which is “primary” depends on dataset, time period, and definitional choices ^{[2] [1] [8]}.