Anthropic says it blocked misuse of its AI that could have supported biological weapons

Anthropic says it has blocked efforts by bad actors to use its artificial intelligence models for malicious activity. Anthropic said Thursday it has blocked efforts by bad actors to use its artificial intelligence models for malicious activity such as cyberattacks, surveillance, and research that could have led to biological weapons. As AI models grow more powerful, elaborate cyberattacks no longer require sophisticated skills and even lone individuals can create threats that would not have been possible even a year ago, Anthropic said.

The company said it has added stronger safeguards in its latest models to restrict biological research that could also be used to make weapons. “The cases we share here aren’t typical misuse, but rather examples of the most notable and novel threat activity we’ve identified to date,” Anthropic said in its third report since March 2025 describing AI misuse. The report includes snippets of the malicious code and AI prompts Anthropic said it found, and urges governments and AI competitors to identify and prevent similar abuse.

“We’re publishing this work because we believe we have a responsibility to disclose malicious misuse of our services. As models become increasingly capable, their risks will increase, unless AI developers and society’s defenders act to make them safer,” the company said. The lengthy report by the AI startup, which is planning an initial public offering this fall, was published the day after one of its researchers announced he’s resigning over concerns that Anthropic and its competitors are not acting responsibly in AI development.

He echoed concerns raised inside and outside of the industry about the technology’s potential to elude human control. Claude was asked to support making a virus more harmful Between December 2025 and August 2026, researchers at Anthropic found misuse by actors ranging from spyware vendors and “politically motivated individuals” to state-sponsored groups spreading propaganda. Among the findings in the company’s report are unnamed actors attempting to use its models for research that could have led to biological weapons.

In one instance, Anthropic said its systems blocked a request for Claude’s assistance in authoring a grant application for scientific funding. “The work discussed in the application involved gain-of-function research (that is, research that genetically alters an organism to create a new or enhanced biological property) on the chikungunya virus. This gain of function research was …

This gain of function research was aimed a…