U.S. government bars Anthropic from giving its newest AI models Fable 5 and Mythos 5 to foreign nationals, forcing the company to disable access for all users due to a discovered security vulnerability.

What happened

The U.S. Commerce Department issued an export control directive on Friday evening (5:21 pm Eastern Time) prohibiting Anthropic from distributing Fable 5 and Mythos 5 to any foreign national, including non-citizen employees in the U.S. Anthropic responded by disabling access to both models for all users to comply with the broad scope of the restriction. Access to its older Claude models, including Claude Opus 4.8, was not affected.

What to watch

Anthropic has stated it believes the directive is a misunderstanding and is working to restore access as soon as possible. The company is also challenging the Pentagon's "supply chain risk" designation in federal court. Policy experts are divided—some view the move as targeted punishment, while others argue Anthropic invited the scrutiny by marketing Mythos as too dangerous to release broadly and highlighting Fable 5's safeguards in press releases.