More than a decade ago, coun­tert­er­ror­ism expert Rita Katz began brows­ing white suprema­cist and neo-Nazi forums. The hate­ful rhetoric and con­stant threats of vio­lence imme­di­ate­ly remind­ed her of the jihadist mil­i­tants she spent her days mon­i­tor­ing, but law enforce­ment and pol­i­cy mak­ers bare­ly paid atten­tion to the Far Right. Now, years of attacks com­mit­ted by extrem­ists rad­i­cal­ized online — includ­ing mass mur­ders at a syn­a­gogue in Pitts­burgh and mosques in Christchurch, New Zealand, as well as the Capi­tol siege — have brought home the danger.