Annie Jacobsen is the author of “Biological War: A Scenario.”

A week-and-a-half ago, AI researcher Jacob Coxon quit his job at Anthropic and warned the public that the people building the world’s most powerful AI systems genuinely believe the technology could “kill us all.” His alarm exploded across X, drawing some 170 million views and counting, as other AI researchers echoed his concern. But what especially interests me is more concrete: How, exactly, does AI kill everyone — or, at least, many millions of us?

I’ve spent decades investigating biological weapons, most recently for my book “Biological War: A Scenario,” which draws on interviews with microbiologists, epidemiologists, and high-ranking government officials to sketch out what a real-world attack might look like. Though the killer pathogen I imagine in my new book is created by a human scientist and not an AI, many of my post-publication conversations have converged on the AI-enabled bio threat.