On June 12, Anthropic cut off access to its Fable 5 and Mythos 5 models after the US government issued an export control order, invoking national security powers to block availability for all foreign nationals.
The directive required Anthropic to comply across the board for every user, despite the company’s open disagreement with the rationale behind the move.
What the US Government Directive Actually Requires
An export control directive is a type of US government order that limits the sharing of certain technologies with foreign nationals. In this instance, the order singled out Anthropic’s Fable 5 and Mythos 5 models, extending the restriction to foreign national Anthropic employees located domestically as well.
Anthropic received the directive at 5:21 p.m. Eastern Time on June 12. The company confirmed that, in order to guarantee full compliance, it had to shut off access for every customer, while stressing that all other Anthropic models continue to be available without interruption.
“Citing national security authorities, the US government has issued an export control directive suspending all access to Fable 5 and Mythos 5 for any foreign national, whether located inside or outside the United States, including foreign national Anthropic employees. The practical consequence of this order is that we must immediately disable Fable 5 and Mythos 5 for all of our customers in order to comply. Access to every other Anthropic model will remain unaffected,” Anthropic stated in an official announcement.
The directive did not detail the precise national security concern. However, Anthropic suspects the government learned of a technique for circumventing, or “jailbreaking,” Fable 5. The company examined a demonstration of the method and described it as minor.
Anthropic further pointed out that the identified vulnerabilities appear straightforward. In addition, other publicly available models, including OpenAI’s GPT-5.5, are capable of uncovering similar weaknesses without needing any jailbreak at all.
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Why Anthropic Disagrees With the Federal Order
Anthropic stressed that Fable 5 was released with more robust safety measures than any model the company had previously deployed. Prior to launch, Anthropic collaborated with the US government, the UK’s AISI, and several independent teams to stress-test the safeguards over thousands of hours.
No tester has yet uncovered a universal jailbreak able to circumvent Fable 5’s defenses across a broad spectrum of cyber capabilities. Because of this, Anthropic implemented a defense-in-depth strategy combining targeted safeguards, active monitoring, and a 30-day data retention policy for Mythos-class models.
“We are following the government’s legal directive and are removing access to Fable 5 and Mythos 5 for all users. That said, we do not agree that the discovery of a narrow, potential jailbreak warrants recalling a commercial model that has been deployed to hundreds of millions of people. If this standard were applied industry-wide, we believe it would effectively bring all new model rollouts by every frontier model provider to a halt,” Anthropic said.
To date, the government has offered only verbal evidence of a narrow, non-universal jailbreak. The reported technique involves instructing the model to review a codebase and patch software vulnerabilities, a capability that is widely available across the industry.
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Anthropic contended that withdrawing a commercial model serving hundreds of millions of users over a limited vulnerability establishes a troubling precedent. Applied broadly, this standard would effectively stop all frontier AI model deployments across the industry.
The company is fully adhering to the directive but has characterized the action as likely a misunderstanding. Anthropic intends to release more technical details within the next 24 hours and is actively working to reinstate access to Fable 5 and Mythos 5 as quickly as possible.
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