Anthropic Says U.S. Directive Forced Fable 5 and Mythos 5 Access Suspension
Anthropic says a U.S. government export-control directive forced it to disable Fable 5 and Mythos 5 access for customers while it disputes the basis for the action.
Anthropic said a U.S. government export-control directive forced the company to suspend access to Fable 5 and Mythos 5, including for foreign nationals inside and outside the United States.
The company said it received the directive on June 12, 2026 at 5:21 PM ET. Anthropic said the order required it to suspend access by any foreign national, including Anthropic employees, and that the practical result was disabling Fable 5 and Mythos 5 for all customers to ensure compliance.
Anthropic said access to its other models is not affected.
- Anthropic says it is complying with the U.S. government directive and disabling Fable 5 and Mythos 5 access.
- The company says the government did not provide specific details of the national-security concern in the letter it received.
- Anthropic disputes that a narrow potential jailbreak finding justifies recalling a commercial model for all customers.
What Anthropic says happened
In its public statement, Anthropic said the U.S. government cited national security authorities and issued an export-control directive covering Fable 5 and Mythos 5. The company said the directive applies to foreign nationals whether they are inside or outside the United States.
Anthropic said the government letter did not include specific details about the national-security concern. The company said its understanding is that the government believes it has become aware of a method for bypassing, or jailbreaking, Fable 5.
Anthropic says it is removing Fable 5 and Mythos 5 access for all users while working to restore access as soon as possible.
The jailbreak dispute
Anthropic said it reviewed a demonstration of the technique and that the demonstration was used to identify a small number of previously known, minor vulnerabilities. The company said those vulnerabilities appear relatively simple and can also be found by other publicly available models without requiring a bypass.
Anthropic also said it has not received disclosure of a concerning non-universal jailbreak that led to a harmful result. According to the company, disclosed potential jailbreaks were either benign responses or minor findings that did not provide Mythos-specific uplift.
The company said the evidence it has received so far is verbal and concerns a narrow, non-universal potential jailbreak that essentially asks the model to read a specific codebase and fix software flaws.
Anthropic's safety argument
Anthropic said its Fable safeguards were tested before launch with the U.S. government, the United Kingdom's AI Security Institute, third-party organizations, and internal teams. The company said no testers have found a universal jailbreak that broadly bypasses the model's safeguards.
The company described its approach as defense in depth: making jailbreaks narrow or expensive to produce, monitoring for successful attacks, and using customer-data retention for Fable to research and mitigate jailbreaks.
- Anthropic says Fable's safeguards reduce misuse risk, including in cybersecurity-related tasks.
- The company says perfect jailbreak resistance is likely not currently possible for any model provider.
- Anthropic says the risk profile of Fable is comparable to other deployed models when paired with monitoring and safeguards.
Company response
Anthropic said it is complying with the legal directive, but disagrees that a narrow potential jailbreak should be grounds for recalling a commercial model deployed at large scale.
The company said government authority to block unsafe deployments should exist through a statutory process that is transparent, fair, clear, and grounded in technical facts. Anthropic said this action does not meet those principles.
Anthropic apologized to customers for the disruption and said it believes the situation is a misunderstanding.
Source materials
The immediate impact is clear: Anthropic says Fable 5 and Mythos 5 access is being disabled to comply with a U.S. government directive.
The broader dispute is about process and evidence. Anthropic is complying with the directive while arguing that the reported jailbreak concern is narrow, not unique to Mythos, and not enough to justify a broad suspension.
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