Anthropic abruptly disabled Fable 5 and Mythos 5 for all customers Friday evening, after the US government issued an export control directive suspending access to the models by any foreign national, inside or outside the United States. Because the order reaches foreign nationals everywhere, including Anthropic’s own employees, the company says the only way to comply was to turn the models off for everyone. Every other Anthropic model is unaffected.

When I started writing this post, around 9:20 p.m. Eastern, I still had access to Fable. At around 10:05 p.m., before publishing, I lost access to Fable 5. This is the message Claude displays in the chat. “There’s an issue with the selected model (claude-fable-5[1m]). It may not exist or you may not have access to it.”

Anthropic says the directive arrived at 5:21 p.m. Eastern, citing national security authorities and, according to Anthropic’s statement, providing no specific details of the concern. Anthropic’s understanding is that the government believes someone found a way to jailbreak Fable 5. The company says it reviewed a demonstration of the technique and that it surfaced a small number of previously known, minor vulnerabilities that other publicly available models can find without any bypass at all.

Axios reported Friday that the Commerce Department moved after another company claimed it had jailbroken Mythos, and that the administration tried and failed to get Anthropic to pause the launch before sending the export control letter.

Anthropic is complying and pushing back at the same time. “We disagree that the finding of a narrow potential jailbreak should be cause for recalling a commercial model deployed to hundreds of millions of people,” the company wrote, saying that the same standard applied across the industry “would essentially halt all new model deployments for all frontier model providers.” The alleged jailbreak, as Anthropic describes it, amounts to asking the model to read a codebase and fix the software flaws it finds, a capability the company says is widely available from other models and “used every day by the defenders who keep systems safe.”

The shutdown hits hardest the teams that moved fastest. Fable 5 launched Tuesday at $10 million input tokens and $50 per million output, and our launch coverage told readers to try it soon. We were, of course, referring to the June 22 usage-credit deadline, not this abrupt federal directive. Anyone who piped Fable 5 into production this week has to scramble to find a replacement. It helps that the rest of Anthropic’s models, Opus, Sonnet, and Haiku, are unaffected. 

The safeguards fight has been simmering since launch. Anthropic kept Mythos 5 itself limited to approved organizations, shipped Fable with broad guardrails, and required 30-day data retention on Mythos-class traffic specifically to detect, track, and shut down jailbreaks. It also plainly said at launch that perfect jailbreak resistance is not currently possible for any provider. The recall came anyway, and Anthropic says the only evidence it has received so far is verbal. 

Anthropic calls the situation a misunderstanding, and it says it’s working to restore access, with more details promised within 24 hours.

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