Anthropic Disables Fable 5 and Mythos 5 After US Government Export Control Directive

Anthropic disabled two of its most advanced cybersecurity AI models on Friday, saying it was responding to a US government export control directive that barred any foreign national from accessing them. The directive covered foreign nationals both inside the United States and abroad, including Anthropic's own employees.

The directive itself has not been made public. According to the company, it cited national security authorities. It is the first time such authorities have been used to curtail the export of AI models rather than chips or hardware.

What the Directive Required

Anthropic said the net effect of the order was that it “must abruptly disable Fable 5 and Mythos 5 for all our customers to ensure compliance.” The company wrote in a statement that its understanding is “that the government believes it has become aware of a method of bypassing, or ‘jailbreaking’ Fable 5,” although the government provided only verbal evidence of this technique. Anthropic reviewed what it believes is the underlying report and found the vulnerabilities identified were minor, previously known, and reproducible using other publicly available models including OpenAI's GPT-5.5.

• Fable 5 and Mythos 5 are cybersecurity-focused models designed to help defend networks and analyze threats.
• The directive bars foreign nationals from accessing the models, a restriction that applies even within the US.
• Anthropic called the move a “misunderstanding” and said it is working to restore access.
• The company warned that if the government’s standard were applied across the industry, it “would essentially halt all new model deployments for all frontier model providers.”

Political Context and Next Steps

The directive arrived two days after Anthropic CEO Dario Amodei published a policy essay calling on the government to have legal authority to block unsafe AI deployments. While the company supports that goal, it said on Friday that any such authority should be created through “a statutory process that is transparent, fair, clear, and grounded in technical facts. This action does not adhere to those principles.”

Anthropic has been under increasing pressure from the Trump administration. In February, Defense Secretary Pete Hegseth designated the company a supply chain risk after contract negotiations for military use of Claude broke down. That label has historically been applied to companies such as Huawei. Earlier this month, Anthropic filed for an initial public offering that investors expect to value the company above $1 trillion, according to the Financial Times. The company said the draft registration statement gives it the option to go public depending on market conditions.

Anthropic apologized for the disruption to customers. It said it believes the government action was based on a misunderstanding and that it is working to restore access as soon as possible.