The two teenagers who killed three worshippers at the Islamic Center of San Diego this week left behind a 75-page manifesto that lays bare the toxic fusion of neo-Nazi ideology, antisemitism and incel rage circulating in the darkest corners of the internet. The gunmen, identified as Caleb Vazquez, 18, and Cain Clark, 17, titled their document “The New Crusade: Sons of Tarrant”, an explicit homage to Brenton Tarrant, the Australian who massacred 51 people at two mosques in Christchurch, New Zealand, in 2019. The pair, who are believed to have met online, wore body cameras to livestream their assault on the messaging platform Discord; video of the rampage quickly circulated on sites such as Watch People Die. The attack ended when Clark shot Vazquez before turning the gun on himself.

Viewed from Washington, the FBI has confirmed it is examining the manifesto, which authorities are treating as evidence of a hate crime. The document repeatedly espouses the white-replacement theory, blaming “the Jews” for all the world’s ills and calling for a race war. The Israeli press, which obtained a copy of the manifesto, highlights its pervasive antisemitism, noting that the shooters, despite targeting Muslims, identified Jews as the “universal enemy”. Meanwhile, analysts in Canberra point to the direct influence of the Christchurch killer, whose manifesto has become a template for far-right extremists globally. From Jakarta, reports note that the document also invokes President Donald Trump by name, suggesting the gunmen sought to co-opt mainstream political rhetoric into their apocalyptic worldview.

The San Diego attack is a stark illustration of how mass shootings have become both ideological acts and performances crafted for online audiences. The Atlantic, in a detailed reconstruction, notes that the teenagers adorned their weapons with white-supremacist symbols and wore patches displaying the Black Sun, a neo-Nazi icon. The manifesto’s tone—rambling, laced with internet memes and incel grievances—mirrors the style of earlier manifestos by far-right killers, indicating a self-aware attempt to join a grim lineage. The glorification of past mass murderers, combined with the live-streamed format, is designed to inspire copycats and ensure the attackers’ place in extremist lore. As investigators across multiple countries piece together the shooters’ online footprint, the case underscores the challenge of detecting and disrupting radicalisation that flourishes in encrypted channels and fringe platforms. The real danger, analysts warn, is not only the immediate loss of life but the perpetuation of a cycle in which each attack fertilises the next.