Anthropic said the directive from the federal government offered no explanation of the underlying national security rationale
(Photo bIllustration by Nikolas Kokovlis/NurPhoto via Getty Images)
Anthropic announced late Friday that it is disabling access to its Fable 5 and Mythos 5 AI models for all customers after the U.S. government issued an export control directive prohibiting their use by any foreign national, whether inside or outside the United States.
Anthropic said it received the directive Friday evening. The Claude maker said it chose to shut down access entirely, given that selective compliance would have required blocking a wide swath of users — among them Anthropic's own foreign-born staff. Access to all other Anthropic models will not be affected, the company said.
Commerce Secretary Howard Lutnick sent Anthropic CEO Dario Amodei a letter outlining the restrictions, according to The Wall Street Journal. Anthropic said the letter offered no explanation of the underlying national security rationale.
The company said it believes the directive stems from a narrow, non-universal jailbreak — essentially a technique involving asking the model to read a specific codebase and identify software flaws. Anthropic said it reviewed what it believes is the report underlying the government's action and concluded that the level of capability it demonstrated is available from other publicly deployed models, including OpenAI's GPT-5.5, and is used by cybersecurity defenders as a matter of routine.
"We disagree that the finding of a narrow potential jailbreak should be cause for recalling a commercial model deployed to hundreds of millions of people," Anthropic said in a statement. "If this standard was applied across the industry, we believe it would essentially halt all new model deployments for all frontier model providers."
Anthropic said it intends to share more details within 24 hours and is working to restore access.
Only days before the shutdown, Anthropic had introduced Fable 5 and Mythos 5 to the public — a milestone for the company, as Fable 5 represented its first general release of a model in the Mythos class. Built on the same underlying architecture, the two differ primarily in their output controls: Fable 5 includes classifiers designed to block responses in high-risk areas such as cybersecurity, while Mythos 5, available to a separately vetted set of organizations, operates with some of those constraints removed. Before launch, Anthropic said it subjected the models to thousands of hours of red-teaming by the U.S. government, the U.K. AI Security Institute, and third-party organizations, none of which found a universal jailbreak.
The shutdown adds a disruption to Anthropic's business at a delicate moment. The company filed a confidential IPO prospectus with the Securities and Exchange Commission earlier this month, disclosing a revenue run rate of $47 billion and a valuation of $965 billion following a recent fundraising round.
This episode is not the first time Anthropic has found itself in conflict with Washington. Earlier this year, the Department of Defense declared the company a supply chain risk — a designation historically applied to foreign adversaries — following the collapse of talks between the two sides. The label obligates defense contractors to certify they are not using Claude in military work. A lawsuit Anthropic filed to challenge the designation remains active.
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