Anthropic said it blocked scientists who used its Claude AI models "in ways that could support biological weapons development."

Anthropic's threat report reveals Claude blocked real bioweapons research attempts in 2026, with state-linked misuse tied to Russia, China, Iran, and Yemen.

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

Claude was developed by Anthropic, a San Francisco-based company founded in 2021 by former OpenAI employees focusing on AI safety and research. Dario Amodei, the co-founder and CEO of Anthropic, had served as vice president of research at OpenAI. His sister Daniela Amodei serves as Anthropic’s president.

Anthropic said Alibaba, Moonshot, Zhipu, DeepSeek, and Xiaomi all tried to use Claude to train their models in various ways.

Anthropic says it disrupted the operation, which compiled ship transponder data, military photos, and satellite imagery to track American vessels

The report details a number of cases involving the misuse of Claude in criminal and state hacking operations, including by Russia-linked groups. Overall, Anthropic said using AI has become so common for hackers that even the most low-level groups now automate broad swathes of their work.

One developer said they feared Anthropic's watermark could lead clients to flag their work as AI-generated and raise questions about authorship.

Trump criticized "negative" voices around the AI industry, saying they are "bringing up things that won't happen."