The Vatican vs. killer robots: Pope Leo XIV takes aim at AI warfare

ROME — Pope Leo XIV on Monday raised the alarm over the use of AI in warfare and called for the technology to be “disarmed” and prevented from “dominating humanity.”

In a document known as an encyclical — a papal letter outlining the church’s perspective on a key topic — Leo said that artificial intelligence should never be used to make lethal decisions and warned that chat bots and other AI tools should never be equated with humans.

The encyclical marks the Catholic Church’s most forceful intervention in the global debate over how artificial intelligence is shaping the future of warfare, labor and society. The text risks putting the Vatican on a collision course with governments racing to deploy AI as a strategic weapon.

The encyclical is the pope’s first since his election last year. Emphasizing its significance, the pontiff took the unusual step of presenting it in person, accompanied by Canadian tech billionaire Christopher Olah, a co-founder of AI giant Anthropic.

Pope Leo XIV attends the presentation of his first Encyclical Letter “Magnifica Humanitas” focused on the rise of artificial intelligence, in The Vatican on May 25, 2026. | Alberto Pizzoli/ AFP via Getty Images

In his letter to Catholic bishops and faithful around the world, Leo described AI not just as a technological issue, but as a turning point for civilization. The encyclical places particular emphasis on the dangers posed by autonomous weapons systems, algorithmic decision-making and the detachment of human responsibility from acts of war.

Leo, who holds a graduate degree in mathematics and once taught physics, does not reject artificial intelligence outright. But his encyclical emphasizes AI must remain subordinate to moral principles and new legal frameworks, ensuring new technologies “truly serve humanity.”

“No algorithm can make war morally acceptable,” he wrote, insisting artificial intelligence must be subjected to the strictest ethical constraints and accountability in warfare. “Any technology that facilitates attacks without seeing the face of human beings lowers the moral threshold of conflict.”