Anthropic Disables Claude Fable 5 and Mythos 5 After US Export Control Order

Anthropic Pulls Its Most Powerful Models

Anthropic has disabled access to Claude Fable 5 and Claude Mythos 5, its two most capable AI models, after receiving a US government export control directive on Thursday evening citing national security concerns. The company said it complied immediately, while publicly disputing the reasoning behind the order.

The Directive

In a statement published on its website, Anthropic said the government required it to suspend all access to Fable 5 and Mythos 5 for any foreign national, "whether inside or outside the United States, including foreign national Anthropic employees." Because the company cannot instantly distinguish domestic from foreign users across its platforms, it disabled both models for everyone. Axios reported that Commerce Secretary Howard Lutnick sent a letter to Anthropic CEO Dario Amodei stating the models would be subject to export controls. Access to all other Anthropic models remains unaffected.

The Jailbreak Dispute

The government's concern centres on a reported method of bypassing Fable 5's safety classifiers. Anthropic said it received only "verbal evidence of a potential narrow, non-universal jailbreak, which essentially consists of asking the model to read a specific codebase and fix any software flaws." The company pushed back hard, saying it reviewed the technique and found it produced results "widely available from other models," including OpenAI's GPT-5.5. Anthropic added it has not received disclosure of any jailbreak that "led to a harmful result" and called the action a "misunderstanding." The episode follows a claim by a researcher known as "Pliny the Liberator," who said days earlier that he had bypassed Fable 5's safety classifiers and published the model's system prompt on GitHub.

Broader Implications

Fable 5 launched on 9 June as the public-facing version of Anthropic's Mythos-class model, with new safeguards blocking responses in cybersecurity and biology. Mythos 5, the unrestricted twin, was limited to vetted government cyber defenders. Anthropic warned that if the standard applied here were used industry-wide, "it would essentially halt all new model deployments for all frontier model providers." The company said it is working to restore access and pledged to share more technical details within 24 hours. The move has also sharpened debate in Europe, where the European Commission's recently published Tech Sovereignty Package has gained new relevance as the bloc weighs its dependence on American technology providers.