An open letter signed by dozens of security experts asked the government to reverse export restrictions on Anthropic's Claude Fable 5 and Mythos 5 models.
June 16, 2026
The security community criticized the US government's decision to restrict Anthropic Claude Mythos and Fable use to foreign nationals, and many have asked the government to reverse course.
Following last week's launch of Anthropic's highly anticipated Fable 5 and Mythos 5 models, the company suspended use of the models for all customers on June 12. This was a direct response to the US government issuing an export control order preventing access to all foreign nationals from using the large language models (LLMs), including those that work for Anthropic themselves. The suspension of the models was to ensure compliance with the order.
In a statement, Anthropic said the government had national security concerns with the frontier models; Mythos in particular is said to be capable of discovering critical vulnerabilities and developing novel critical exploits in software. Security experts have warned that Mythos, and models like it, will change the vulnerability remediation landscape, and organizations must become "Mythos-ready" for the threat actors that will attempt to abuse the LLM.
