Anthropic shuts down Fable 5 and Mythos 5 after U.S. export control order

Anthropic is disabling access to Fable 5 and Mythos 5 for all customers after the U.S. government issued an export control directive restricting access to the models by foreign nationals, including Anthropic employees.

The company said it received the directive today at 5:21 p.m. ET. The order cited national security authorities but did not provide specific details of the government’s concern, according to Anthropic.

Anthropic said the practical result is that it must abruptly suspend both models for all customers to ensure compliance. Access to all other Anthropic models will not be affected.

The company said its understanding is that the government believes it has become aware of a way to bypass Fable 5’s safeguards. Anthropic disputed the severity of the issue, saying the technique appeared narrow rather than universal and had only been shown identifying a small number of previously known minor software vulnerabilities.

Anthropic said those capabilities are already available from other public models, including OpenAI’s GPT 5.5, and are routinely used by defenders to find and fix security issues. The company said it has not received evidence of a concerning jailbreak that led to a harmful result or showed unique uplift from Mythos 5.

The move marks a sharp escalation in Washington’s oversight of frontier AI models. Export controls have historically focused on chips and other sensitive technologies, but the directive directly targets model access itself, including access by foreign nationals inside the United States.

Anthropic said it supports the government’s ability to block unsafe deployments through a transparent and technically grounded process. But the company argued this order does not meet that standard and warned that applying the same threshold across the industry could effectively freeze new frontier model launches.

“We believe this is a misunderstanding and are working to restore access as soon as possible,” the company said.

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