Digital Aftershocks: Online Mobilization and Violence in the United States

Against a backdrop of escalating political violence and deepening polarization in the United States, our report examines how extremist actors across the ideological spectrum are exploiting digital platforms to respond to, amplify, and glorify violence. Drawing on open-source intelligence collected between March and September 2025, the report traces how far-right, far-left, violent Islamist, and nihilistic violent extremist (NVE) communities use cross-platform strategies to recruit followers, justify violence, and sustain propaganda networks.

At a time of polarized debate over speech and safety online, the report brings clarity to the legal boundaries between protected expression and unlawful threats or incitement under US constitutional doctrine. It highlights the growing convergence around antisemitic targeting, the asymmetric enforcement of terrorist designations, and the rise of “nihilistic” actors seeking digital notoriety rather than political change.

The report includes a series of practical, rights-respecting recommendations for platforms and policymakers to disrupt violent networks, strengthen transparency, and safeguard both public safety and freedom of expression.

Mariana Olaizola Rosenblat joined the NYU Stern Center for Business and Human Rights in August 2022 as a Policy Advisor on technology and law. Her research and advocacy span online gaming, encrypted messaging, global platform regulation, and 3D immersive ("metaverse") technologies. Her work has been featured in USA Today, ABC News, The New York Times, the BBC, The Washington Post, and Axios, among other outlets. Prior to joining the Center, Mariana taught at the University of Chicago Law School and consulted for several international human rights organizations, including the UN High Commissioner for Refugees (UNHCR), the Council of Europe, and the Center for Diversity and National Harmony in Myanmar. Mariana received her JD from Yale Law School and her BA in Political Theory from Princeton.

Luke Barnes is a Senior Research Scientist at the Stern Center. His interests include online radicalization, malign digital propaganda tactics, and the geopolitics of AI development. Prior to Stern, Luke worked as a threat context analyst for Microsoft. Luke holds an MA in Security Studies from the Fletcher School of Law and Diplomacy and a BA in Political Science from Columbia University.

Dr. Tessa Harmon is a scholar of religion whose work examines the entanglements of race, religion, and nationalism in the development of white nationalist ideology in the United States. She recently completed her PhD on the religious and philosophical foundations of the “white genocide” myth at the University of California, Riverside, tracing its roots through modern Aryanism and antisemitic historical revisionism. At the Center, she will focus on preparing her first book manuscript based on this research while also launching a new project that examines the intersections between far-right and far-left forms of antisemitism in contemporary U.S. political culture.