In 2017, a small crew gathered in a windowless Pentagon room to put AI at the heart of how America makes war. Led by Drew Cukor, an unyielding Marine Corps colonel driven by the deaths of US troops and the prospect of war with an AI-equipped China, the Project Maven team raced to send AI into combat, igniting controversy and forever changing the US military. Summoning the mayhem of a tech startup, the Maven team wrestled Pentagon bureaucrats and each other. They enlisted an initially reluctant Silicon Valley, supercharged the growth of Palantir, and sent algorithms made by Amazon, Microsoft and others into hot wars. Maven fielded technology to identify targets at speed and scale, developed AI-infused command systems, and learned where AI fails. The prospect of machines making independent decisions about life and death alarmed members of the US military across all ranks and the project sparked a revolt amongst thousands of tech workers at Google. Yet today, Maven’s AI-enabled systems operate in every branch of the US military and its lessons are folded into developing autonomous technology set to be on the front lines of future war. Project Maven and its legacy sit at the intersection of colliding trends: America’s insecurity about declining global power, the technological revolution driving AI into every aspect of society, the dominance of Big Tech, all-encompassing surveillance, and the ambitions of China’s growing military. As the second Trump administration pours money into military AI and autonomy while the UN Secretary-General clamours for a ban on killer robots, this book investigates whether AI will improve accuracy and save lives or if a fundamentally unreliable black-box technology will unleash mistakes and atrocities at scale. Drawing on more than 200 interviews with insiders and opponents, this compelling narrative tells the definitive story of how AI warfare, once the stuff of apocalyptic science fiction, has become a reality.