Anthropic has disabled access to its Fable 5 and Mythos 5 AI models after the US government issued an export control directive Friday afternoon, citing national security authorities. The company received the order at 5:21 p.m. ET and moved to cut off all users rather than risk non-compliance.
The directive targeted foreign nationals, covering anyone “whether inside or outside the United States, including foreign national Anthropic employees.” Rather than attempt to screen individual users, the company shut down the models entirely, affecting hundreds of millions of people. All other Anthropic models remain available.
Fable 5 launched only days ago and was notable for being the first time Anthropic made such an advanced model broadly available to the public. The release included new safeguards designed to block responses in high-risk areas, particularly around cybersecurity. Its companion model, Mythos 5, built on the earlier Claude Mythos Preview, which had drawn significant attention from Wall Street and government officials for its advanced cyber capabilities when it debuted in April.
The government did not disclose specific details about its national security concern, but Anthropic says it understands the directive stems from a method of bypassing the model’s safeguards. After reviewing a demonstration of the technique, the company concluded it produced only minor, previously known vulnerabilities that other publicly available models, including OpenAI’s GPT-5.5, can also surface. The company argues that the capabilities shown are widely used by security professionals on a daily basis.
Anthropic pushed back firmly on the premise of the order. The company maintains it adopted a “defense in depth” strategy for Fable 5, combining narrow jailbreak resistance with active monitoring, and that no universal jailbreak has been found. It also argued that applying this standard across the industry would effectively halt all new frontier model deployments.
The company said it is complying with the directive but characterized the action as a misunderstanding, pledging to work toward restoring access.
The incident is the latest in an escalating conflict between Anthropic and the US government. Earlier this year, the Department of Defense declared the company a supply chain risk, a designation historically applied to foreign adversaries, and required defense contractors to certify they would not use Claude in military work. Anthropic’s lawsuit against the Trump administration over that blacklisting is still ongoing.
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