It may sound like science fiction, but scientists, security services, and international organizations are grappling with the possibility that artificial intelligence could be misused to develop biological weapons. As biotechnology enables pathogens to be analyzed and altered with ever greater precision, and AI systems evaluate vast amounts of data at astonishing speed, experts warn that modern technologies could, in the long term, be turned toward spreading disease deliberately.
Security services are already sounding the alarm. In October 2026, Ken McCallum, head of the British domestic intelligence service MI5, warned that artificial intelligence could increase the risk from existing, or new, biological weapons, including from non-state actors.
A September 2026 report by the American AI company Anthropic highlighted how topical the debate has become. The company said it had identified and blocked numerous attempts to use its AI assistant Claude in connection with possible biological weapons research, including grant applications for so-called "gain-of-function" research and projects on avian influenza variants potentially among the most transmissible to mammals.
Anthropic stressed that such research can also serve medical prevention, despite potential military applications. Distinguishing legitimate science from possible misuse remains one of the biggest problems in controlling modern biotechnology.
Concerns about biological weapons are by no means new. Many pathogens, including bacteria, viruses, fungi, and certain biological toxins, can be weaponized. Plague, smallpox, and botulinum toxin are familiar examples, but anthrax is among the most notorious: its resistant spores can survive a long time in the environment, and it has been a focus of state biological weapons programs. The World Health Organization and the United Nations Office for Disarmament Affairs define a biological weapon as the targeted release of such substances to injure people, animals, or plants.
Such a weapon usually has two components: the biological substance itself, called the "agent," and a "delivery mechanism" such as missiles, spraying systems, or contaminated food. Together with atomic and chemical weapons, biological weapons form the so-called ABC category and are often counted as weapons of mass destruction.
Biological and chemical weapons differ in their mode of operation. Chemical agents such as sarin or mustard gas injure through toxic effects that often appear within minutes or even seconds, as in the gas attacks of World War I, the Syrian civil war, and Saddam Hussein's Iraq. Biological weapons instead cause infectious disease, with effects emerging hours, days, or weeks after deployment. Some pathogens can spread from person to person, making the outcome particularly hard to predict.
Biological weapons are prohibited under international law. The Biological Weapons Convention entered into force in 1975 and has been ratified by 189 countries. Building on the 1925 Geneva Protocol, which banned the use of biological weapons in warfare, it prohibits their development, production, stockpiling, acquisition, retention, and transfer, and obliges parties to destroy all stocks, production sites, and means of conveyance. Only a few countries, including Israel, Egypt, and Syria, have not signed or not ratified the agreement.
Chemical weapons, by contrast, are overseen by the Organization for the Prohibition of Chemical Weapons, which can conduct inspections and supervise the destruction of stockpiles. No comparable system exists for biological weapons, partly because states fear inspections could expose sensitive medical, biotechnological, or pharmaceutical research; control therefore rests largely on transparency, voluntary reporting, and good faith. The ban's limits were starkly illustrated in the United States in 2001, when letters containing anthrax spores sent weeks after the September 11 attacks infected 22 people and killed five.
Biological weapons are also difficult to expose because much of the relevant technology has civilian applications, a dilemma experts call the dual use problem: the same laboratory equipment used for vaccines and medicines could, in theory, serve military research. An attack can initially look like a natural disease outbreak, and only extensive investigation can establish whether a pathogen was released deliberately. Perhaps that helps explain why biological weapons have been deployed throughout history, from poisoned wells to plague victims' corpses catapulted over the walls of besieged towns, though the effectiveness of such methods is disputed.
