Anthropic blocked attempts to use Claude for biological weapons development

Anthropic blocks 'malicious use' of AI that could develop biological weapons

Anthropic's threat intelligence report reveals that between December 2025 and August 2026, Claude Haiku, Sonnet, and Opus were used in attempts that could support biological weapons development. The company disrupted five such cases. The report also flags misuse for conventional weapons software, a Russia-linked cyber espionage campaign, an Iranian propaganda institution, and distillation by Chinese AI firms. Anthropic calls biological misuse one of the most serious frontier-model risks and says it has folded findings into its processes and shared them with authorities.

Why it matters: Anthropic voluntarily disclosed safety intervention data — 5 bioweapon misuse attempts blocked across Haiku, Sonnet, and Opus, with named threat actors including Russia. This is hard evidence on frontier model safety governance, not a PR piece. Score held back from 85+ only be...