Anthropic said it was removing access to its Fable 5 and Mythos 5 models for all users after receiving a US government export-control directive that barred their use by any foreign national. The company said the restriction applied to people inside and outside the United States, including its own foreign-national employees, making a universal customer shutdown necessary for compliance.
Other Anthropic models were not affected by the action, according to the company’s statement. Anthropic said it received the directive at 5:21 p.m. Eastern time on the event date and began disabling the two named systems abruptly. It apologized to customers and said it was working to restore access, but gave no timetable for doing so.
The government’s letter did not explain the specific national-security concern, Anthropic said. The company’s understanding was that officials had been shown a way to bypass safeguards on Fable 5. Anthropic described the reported method as narrow rather than universal and said it involved asking the model to inspect a particular codebase and repair software flaws. Those descriptions represent Anthropic’s account; the supplied evidence does not include the directive or the government’s technical assessment.
Anthropic said it reviewed a demonstration in which the technique identified a small number of previously known, minor vulnerabilities. It argued that the flaws were relatively simple and could also be found by publicly available models without the same bypass. The company further said it examined a report it believed prompted the directive and concluded that the demonstrated capability was already widely available, including from OpenAI’s GPT-5.5, and routinely used by security defenders. No independent test results accompanied the statement.
The company characterized the evidence received from the government up to that point as verbal information about one potential jailbreak. It committed to sharing more details within 24 hours. Until those details or a government account are available, the technical scope of the bypass and the legal basis for the directive cannot be assessed from the company’s statement alone.
Anthropic said it was complying with the order while contesting the standard behind it. In its view, recalling a commercial model used by hundreds of millions of people because of a narrow potential bypass would, if applied across the industry, impede new deployments by every frontier-model provider. That claim is the company’s policy argument, not a measured forecast.
The statement also accepted that government should be able to stop unsafe deployments, but called for a statutory process that is transparent, technically grounded and procedurally clear. Anthropic said the present action did not meet those conditions. The immediate outcome was nonetheless unambiguous: Fable 5 and Mythos 5 access stopped broadly because Anthropic said it could not otherwise guarantee that foreign nationals were excluded, while the company sought to resolve what it described as a misunderstanding.
