Concerns over the potential use of artificial intelligence (A.I.) in the development of biological weapons have been escalating among scientists and biosecurity experts. In recent months, researchers and technology executives have issued warnings about A.I.’s capacity to accelerate the design and synthesis of dangerous pathogens, raising the prospect of a new biological arms race.

In April, experts cautioned that chatbots could readily provide assistance on making pathogens more harmful. By June, an open letter signed by scientists and A.I. leaders called for stricter controls on DNA fabrication, noting that A.I. now enables the rapid creation of toxins and viruses. In August, researchers demonstrated how A.I. models had been used to generate virus genomes previously unseen in nature. Most recently, the artificial intelligence company Anthropic publicly disclosed blocking attempts by users who appeared to be seeking to weaponize pathogens. Anthropic’s CEO, Dario Amodei, subsequently called for a slowdown in A.I. development and urged comprehensive bans on its use for biological weapons production.

Despite these developments, some experts maintain that the current generation of chatbots does not represent a fundamental escalation of biological security risks. Drew Endy, a synthetic biologist at Stanford University, described the present impact as modest but acknowledged that risks could increase as models specialized in biological research improve. These advanced systems can already design viable viral genomes not found in nature, which might eventually be harnessed for malicious purposes.

Biological weapons comprise viruses, bacteria, fungi, or toxins engineered to harm humans or animals, distinct from chemical weapons such as nerve agents. The use of disease in warfare dates back centuries, from medieval attempts to spread plague-infected corpses to more systematic efforts during World War I. Although international protocols such as the Geneva Protocol and the Biological Weapons Convention sought to limit such weapons, Cold War powers nonetheless developed extensive arsenals. While the United States destroyed its stockpiles after 1975, the Soviet Union reportedly continued weaponization research in secret.

Since World War II, biological weapons have caused relatively few known casualties, a fact that specialists attribute to a combination of deterrence, technical hurdles, and possibly undisclosed events. However, the accessibility of modern biotechnologies is a continuing concern. DNA synthesis, now faster and more affordable, allows for the recreation of viruses that no longer exist in nature, as demonstrated in 2016 when Canadian scientists synthesized horsepox virus from sequenced DNA fragments.

A.I. models can assist with information retrieval and data analysis relevant to pathogen development, potentially providing a more sophisticated means for bad actors to gather insights than traditional search engines. However, Dr. Thomas Inglesby of the Johns Hopkins Center for Health Security noted that current A.I. lacks true understanding of biology beyond existing scientific knowledge.

Some researchers are developing models that learn directly from raw biological data. For example, Stanford and the Arc Institute created Evo2, which analyzed DNA sequences across millions of species and generated new enzyme variants. After further training on viral genomes of microvirid viruses—harmless viruses that infect bacteria—Evo2 produced thousands of synthetic genomes, some of which yielded viable viruses in laboratory settings. The developers have refrained from training Evo2 on human-infecting viruses, but warn that future iterations might have the capacity to design harmful pathogens, including variants of deadly viruses like smallpox.

Such advances raise fears of a resurgence in biological arms competitions among states. Recent attempts to query Anthropic’s A.I. about influenza and other pathogens appeared to originate from government laboratories rather than independent individuals, suggesting official interest in these capabilities. Dr. Endy warned that governmental involvement could revive tensions reminiscent of Cold War biological weapons programs, citing current mutual accusations among nations including the United States, Russia, China, North Korea, and Iran.

Experts agree that mitigating these risks will require renewed international cooperation and regulation. Measures include enforcing DNA synthesis screening protocols, though the Biden administration’s efforts in this area face challenges following a suspension under the previous administration. Beyond restricting access, Dr. Endy emphasized the importance of proactive defenses against infectious diseases, whether engineered or naturally occurring. He advocates for enhanced surveillance infrastructure in public spaces such as hospitals and schools to detect airborne threats early and enable timely responses.

While the technological landscape is evolving rapidly, experts stress that biological risks are tangible and manageable, not abstract or insurmountable. Continued investment in biosecurity research, combined with robust policy frameworks, remains crucial to preventing future biological threats.