Anthropic Reports Five Potential Biological-Weapons Misuse Cases

Anthropic says it identified five cases between December 2025 and August 2026 in which users sought Claude assistance that could support biological-weapons development, while stressing that it does not assert harmful intent. The cases involved chikungunya gain-of-function work, mammal-adapted avian influenza, orthopoxvirus proposal drafting, a venom-peptide atlas and computational toxin redesign. Anthropic withheld the researchers’ identities, institutions, countries and sensitive techniques. The company says it banned associated accounts, strengthened safeguards and shared findings where appropriate. Its wider report covers disrupted activity across seven categories of harm.