By Katarzyna Jaskoa, Gary LaFree, James Piazzac , and Michael H. Beckerd

Although political violence has been perpetrated on behalf of a wide range of political ideologies, it is unclear whether there are systematic differences between ideologies in the use of violence to pursue a political cause. Prior research on this topic is scarce and mostly restricted to self-reported measures or less extreme forms of political aggression. Moreover, it has generally focused on respondents in Western countries and has been limited to either comparisons of the supporters of left-wing and right-wing causes or examinations of only Islamist extremism. In this research we address these gaps by comparing the use of political violence by left-wing, right-wing, and Islamist extremists in the United States and worldwide using two unique datasets that cover real-world examples of politically motivated, violent behaviors. Across both datasets, we find that radical acts perpetrated by individuals associated with left-wing causes are less likely to be violent. In the United States, we find no difference between the level of violence perpetrated by right-wing and Islamist extremists. However, differences in violence emerge on the global level, with Islamist extremists being more likely than right-wing extremists to engage in more violent acts.

Political violence in the United States has increased in recent years and shows no signs of declining.1 This trend was underscored in September 2025 by the assassination of conservative activist Charlie Kirk at Utah Valley University. In the two weeks before and after Kirk’s killing, shooting incidents in Colorado, Minneapolis, and Dallas seized public attention.2 Executive Summary Amid growing concern about the relationship between online rhetoric and real-world violence, this report examines how violent extremist actors across the ideological spectrum use digital platforms to respond to, amplify, and exploit acts of political violence in the United States. Drawing on opensource intelligence (OSINT) gathered initially from March 24 to June 6, 2025, and then extended to include a period following Kirk’s assassination, this analysis reveals sophisticated cross-platform strategies employed by far-right, far-left, violent Islamist, and nihilistic violent extremist (NVE) actors. This report uses “violent extremist” to refer to individuals who support or commit ideologically motivated violence to further political goals, as well as those who commit violence driven by generalized hatred rather than a coherent ideology. Key Findings • Violent extremist groups systematically exploit trigger events—high-profile incidents of violence—to recruit supporters, justify their ideologies, and call for retaliatory action. • These groups employ multi-platform strategies, using mainstream sites like X for visibility and recruitment while maintaining a presence on private or semi-private platforms for coordination and more extreme content. • Far-right groups capitalized on cases like the Austin Metcalf stabbing and the Iryna Zarutska killing to advance narratives of White victimhood and justify threats against perceived enemies. • Activities of both far-left and far-right networks revealed a troubling convergence around antisemitic targeting. • Violent Islamic groups are more aggressively monitored than domestic groups espousing similar levels of violence. • Violent Islamist groups, facing stricter moderation than domestic extremists, have migrated to decentralized platforms like Rocket.Chat while disseminating symbolic propaganda elsewhere. • Nihilistic Violent Extremist (NVE) communities glorify violence across ideological lines for shock value and digital notoriety, making their threats harder to predict based on political triggers. This report aims to bring clarity to a conversation clouded by vagueness and partisanship. It first maps the domestic threat landscape, offering timely examples of online violent discourse from across the ideological spectrum targeting US individuals or institutions, and sets out a clear definitional framework for types of speech that carry legal significance under US constitutional doctrine. It closes with practical recommendations for online service providers and policymakers.

PNAS 2022 Vol. 119 No. 30 e2122593119