The U.S. government on Friday ordered Anthropic to immediately suspend foreign access to Fable 5 and Mythos 5, its two most advanced artificial intelligence models, citing national security concerns tied to a reported method of bypassing the models’ safety restrictions.
The directive, issued late Friday afternoon by Secretary of Commerce Howard Lutnick in a letter to Anthropic Chief Executive Dario Amodei, placed the two models under export controls that prohibit use by foreign nationals, whether inside or outside the United States.
Because of the scope of the restrictions, which includes foreign-born Anthropic employees, the company announced Friday evening that it disabled the models to ensure compliance. Access to the company’s other AI models was not affected.
Fable 5 and Mythos 5 had been released earlier this week, with Anthropic describing them as the most capable systems it had ever deployed. Mythos was available to members of Project Glasswing, which allowed selected cybersecurity companies to use the model to identify and address security flaws.
It’s unclear how the Commerce Department action affects Project Glasswing. Anthropic did not respond to a request for comment.
The Commerce Department‘s letter did not detail the specific national security concern. In its blog post Friday night, the company said its understanding is that the government became aware of a technique for “jailbreaking” Fable 5, a term for methods that circumvent a model’s built-in safety guardrails. According to Anthropic, the government provided only verbal evidence of what it described as a “narrow, non-universal jailbreak,” which essentially involved prompting the model to read a specific codebase and identify software flaws.
Anthropic disputed the severity of the finding. The company said it reviewed a report it believes formed the basis of the government’s directive and found that the capabilities demonstrated were already available in other publicly accessible models, including OpenAI’s GPT-5.5. The company said those same capabilities are used routinely by cybersecurity professionals for defensive purposes.
Katie Moussouris, chief executive of the cybersecurity firm Luta Security, posted on BlueSky Saturday that the issue stems from “Defense Oriented Prompting,” a security-first method of engineering AI system instructions that treats natural language as code.
Other reports claimed that Amazon was responsible for flagging the security issues in the model. The company did not respond to CyberScoop’s request for comment.
Anthropic acknowledged in its statement that perfect jailbreak resistance is not achievable for any model provider, and said it had designed Fable 5 around a “defense in depth” strategy, combining narrow jailbreak resistance with active monitoring. The company said no testers had found a universal jailbreak capable of broadly bypassing the model’s safeguards.
“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 wrote. “If this standard was applied across the industry, we believe it would essentially halt all new model deployments for all frontier model providers.”
Friday’s directive is the latest episode in a prolonged dispute between Anthropic and the Trump administration. In February, President Donald Trump moved to bar Anthropic’s products from federal agencies after the company sought stronger restrictions on how the Pentagon used its technology.
Despite that, as Anthropic released Mythos under Project Glasswing, the National Security Agency was given Mythos 5 to conduct offensive cyber operations. Earlier this month, Trump signed an executive order directing federal agencies to bolster cyber defenses and establish a voluntary mechanism for the government to gain early access to powerful AI models before deployment.
The administration’s stated rationale for Friday’s action drew widespread skepticism from researchers and analysts. Dean Ball, a senior fellow at the Foundation for American Innovation, called the move “baffling.” Chris McGuire, a senior fellow at the Council on Foreign Relations, said targeted export controls on model access could be a legitimate policy tool, but called the across-the-board restriction “highly questionable” and the deemed export provisions — which restrict foreign nationals inside the U.S. — “just absurd.”
The broader implications for the AI industry remain uncertain. Aaron Levie, chief executive of Box, described the directive as “a big turning point for AI regulation,” arguing that the government’s willingness to deem specific models too powerful for certain uses establishes a precedent with potentially far-reaching consequences.
Other tech leaders in the government supported the action.
“We fully support @POTUS and @SecWar in prioritizing national security and the security of our warfighters, DIB partners, critical infrastructure, international partners and allies,” DOD CIO Kirsten Davies wrote in a social post on X. “Some things are simply more important than revenue cycles, clickbait, and pre-IPO valuation. America First. Always.”
Anthropic said it believes the situation stems from a misunderstanding and is working to restore access as soon as possible.
