Anthropic blocks possible attempt to use AI to make biological weapons

Anthropic says it has identified and disrupted attempts to use its AI model for "malicious activity" which could support the development of biological weapons.

The findings, made in the firm's recent threat intelligence report, is the latest in a growing series of warnings from AI researchers and industry insiders about the technology's potential risks to humanity.

The warnings have prompted calls to action, with US Senator Bernie Sanders demanding a pause on advanced AI development and a ban on artificial superintelligence.

President Donald Trump has so far rejected such fears, saying on Thursday he was concerned "if we don't win AI, we're going to be put in a very bad position".

The company published its latest threat intelligence report, external on Thursday.

Such reports have become a regular feature across the AI industry as firms seek to demonstrate how they identify and disrupt attempts to misuse their models.

This includes Google, which wrote on Tuesday, external that a person had attempted to use its AI tool, Gemini, to obtain a "complete, step-by-step technical guide for synthesizing weaponised biological agents".

Claude, Anthropic's AI model was also used by actors linked to a Russia-based cyber espionage campaign and by an Iranian propaganda institution, according to its report.

The cases of concern detected over the past eight months ranged from fake dating apps and hotel Wifi scams, to surveillance built to identify dissidents.

Anthropic has also accused Chinese AI firms of trying to replicate Claude's capabilities.

The lengthy report lists cases in which suspected state-sponsored groups, criminals, spyware vendors, state propaganda institutions and politically motivated individuals misused its technology.

"Malicious use" of its Claude Haiku, Sonnet, and Opus models was disrupted between December 2025 and August 2026, it said.

None of the misuse cases involved Claude Fable or the powerful Mythos-class models, with the exception of one instance of distillation - the process for training smaller AI models using larger, more expensive models.

As well as detecting the use of its models for cyber and influence operations, surveillance, scams and fraud and weapon development, Anthropic said it had blocked scientists who used its AI in ways that could support biological weapons development.

The report highlighted "five case studies of actors using our models in ways that could support biological weapons development".

Biological misuse, it said, is "one of the most serious risks of frontier AI model". Without the correct safeguards, such capabilities "could have catastrophic consequences", Anthropic said.

"The same information that can be used to develop a biological weapon could also be used to develop, for example, a vaccine or a cure for a disease," Anthropic said.

Jacob Klein, the head of threat intelligence at Anthropic, told the New York Times, external it was "an incredibly nuanced situation".

"You are not seeing someone in a comic book kind of way say, 'Hey, I want to build a biological weapon to kill everybody,'" he said.

The report also noted six cases where Claude was used "to develop software for conventional weapons, including firearms, missiles, armed drones, bombs, and other munitions, as well as the targeting and control systems that operate them".

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The report indicated that cybercriminals and state-backed hackers have increasingly used its technology to assist their operations.

Hacking group ShinyHunters, as well as China-based labs, were among those named in the report.

The report also said that a hacking group whose work is consistent with the Russia-based Midnight Blizzard allegedly used AI to build a system that automatically detected when its malware was flagged by security defences and rewrote code until it evaded detection.

The California-based company said it had incorporated its findings into its processes "to better prevent, detect, and disrupt these activities in the future".

Anthropic said it had shared intelligence with authorities and industry partners where appropriate.

The report - the company's first this year - comes after a top safety researcher at Anthropic warned AI is advancing so quickly he believes there is a greater than 10% chance it "could kill all humans" within the next decade.

In an article published on 6 September, OpenAI chief scientist Jakub Pachocki called for the industry to implement "voluntary slowdowns" until safeguards are set.