Days after Anthropic globally rolled out Claude Fable 5, a “safe” version of their frontier AI model Claude Mythos, the U.S. government has asked the AI company to suspend the access of Fable 5 and Mythos for all except U.S. nationals, citing national security concerns.

According to a latest statement released by Anthropic on Saturday,  the directive issued by the government did not specify details of its national security concerns. It further mentioned that the directive applies to foreign nationals, whether inside or outside the US, including the company’s own foreign national employees. 

In April, Anthropic claimed they had developed Claude Mythos, their frontier AI model deemed much more capable than existing frontier models, thereby the company refused to launch it citing safety challenges posed by Mythos. A week ago, Anthropic launched Claude Fable 5, claiming its a version of its Mythos model with necessary safeguards.

“The net effect of this order is that we must abruptly disable Fable 5 and Mythos 5 for all our customers to ensure compliance. The access to all other Anthropic models will not be affected,” the company clarified in its official statement.

“The letter did not provide specific details of its national security concern. Our understanding is that the government believes it has become aware of a method of bypassing, or “jailbreaking” Fable 5,” it further highlighted.

The company said it reviewed a demonstration of the technique and found that it could only identify a small number of previously known, minor vulnerabilities. Anthropic stated that these vulnerabilities were not unique to Fable 5, adding that other publicly-available models were capable of  discovering them as well without requiring a bypass. 

Anthropic maintained that its position with respect to Fable’s safeguards was laid out in their launch blog post. 

While the company said that it will comply with the government’s order, it argued that the reported jailbreak vulnerability was limited and  cannot be a cause for recalling a commercial model deployed to hundreds of millions of people.  It warned that if this standard was applied across the industry, then it would halt all new model deployments for all frontier model providers. 

“We have reviewed a report that we believe is the basis of the government’s directive and validated that the level of capability displayed there is widely available from other models (including OpenAI’s GPT-5.5), and is used every day by the defenders who keep systems safe. We will share more details over the next 24 hours,” the company informed.

Recently, Anthropic CEO Dario Amodei  issued an essay titled “Policy on the AI Exponential” in which he urged policymakers to speed up the regulation to deal with the risks and opportunities arising from the exponential growth of artificial intelligence. 

Following the US government’s order, the company argued that as per its recent suggested policy the government should have the ability to block unsafe deployments, as part of a statutory process that is transparent, fair, clear, and grounded in technical facts, but this action does not adhere to its principles.

Also Read: Explained: Why is Anthropic Calling for a Global Pause on Frontier AI?