In the space of 36 minutes on March 15, 2019, it is alleged that Brenton Tarrant, an Australian far-right extremist, fatally shot 51 people in two mosques in Christchurch in the deadliest terrorist attack in New Zealand’s history. What was unique about Tarrant’s attack—at least insofar as extreme-right terrorism is concerned—is that he livestreamed his atrocity on Facebook and in doing so, highlighted the Achilles heel of such platforms when faced with the viral dissemination of extremely violent content.