"To date, the government has only given us verbal evidence of a potential narrow, non-universal jailbreak," Anthropic wrote after receiving the order on June 12.
Export-control directive received at 5:21pm ET on June 12
Anthropic says it received a US government directive citing "national security" authorities at 5:21pm ET on June 12 that bars access to its two most capable models, Fable 5 and Mythos 5, by any foreign national — whether inside or outside the United States. The order explicitly covers Anthropic's own foreign-national employees. Anthropic says the directive's net effect is that it must disable both models for all customers in order to comply.
Company suspends Fable 5 and Mythos 5 worldwide; Claude Opus 4.8 unaffected
In response, Anthropic suspended access to Fable 5 and Mythos 5 for users worldwide. The company described those models as its "two most capable" systems and said all other models remain available; Anthropic specifically named Claude Opus 4.8 as unaffected. The timing amplified the disruption: Anthropic began rolling out Fable 5 on June 9 and had made it free to all Pro, Max, and Enterprise customers through June 22. That model, which was handed to millions three days earlier, is now offline for everyone.
Fable 5 and Mythos 5: safeguards, access rules, and the reported jailbreak
Anthropic framed Fable 5 as the "safeguarded sibling" of Mythos 5, stating both share the same underlying model but that Fable adds protective controls. According to the company, Fable 5 blocks or diverts sensitive cybersecurity, biology, and chemistry queries. By contrast, Anthropic says Mythos 5 is less restricted but is routed only to "vetted government cyberdefenders and life sciences partners."
Anthropic's interpretation of the government's order is that it stems from a reported way to "jailbreak" Fable 5. The company said it reviewed a demo presented to the government and concluded it found only "minor, already‑known bugs, the kind other publicly‑available models are able to discover without any bypass." Anthropic also stated, "Our understanding is that one potential jailbreak was shared with the government."
Developer notice: fallbacks, errors, and migration guidance
Anthropic issued a developer notice describing the immediate technical impact. New sessions that would have used Fable 5 will now fall back to a user's default model or to Opus 4.8. Existing Fable 5 sessions, the company said, will end with an error, and Platform requests routed to Fable 5 will fail. Integrators were instructed to migrate to other models.
How government cyberdefenders, enterprise customers, and integrators are affected
- Government cyberdefenders and life sciences partners: Anthropic says Mythos 5 had been routed only to vetted government cyberdefenders and life sciences partners, and the directive removes that access as well — at least temporarily — by forcing a universal disable. Those defenders lose access to a model Anthropic describes as unrestricted.
- Enterprise customers (Pro, Max, Enterprise): Millions of users who gained free access to Fable 5 beginning June 9 now find the model offline and are being shifted to default models or Opus 4.8. Anthropic told these customers that new sessions will fall back and existing sessions will error, creating an immediate operational change for any workflows that had adopted Fable 5.
- Integrators and platform partners: Platform requests to Fable 5 will fail and Anthropic has told integrators to migrate to other models. That requires technical changes and testing for integrators who had built on Fable 5's APIs or relied on its safeguard behavior.
Anthropic said it is complying with the government's legal directive but disputed the substantive rationale: "We are complying with the government's legal directive and are removing access to Fable 5 and Mythos 5 for all users. However, 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." The company warned that applying this standard industry-wide "would essentially halt all new model deployments for all frontier model providers," and pointed to other vendors — naming OpenAI's GPT-5.5 — as places where the capability in question is also available and "used by defenders every day."
Anthropic said it views the order as a misunderstanding and that it is working to restore access, promising "more details within 24 hours." The immediate, concrete outcomes are clear: Fable 5 and Mythos 5 are offline, customers have been redirected to fallback models, and integrators must migrate. What remains to be seen — and what Anthropic highlighted by noting the government provided only "verbal evidence" — is whether the government will provide written, technical substantiation for the directive and whether any remediation or rule adjustments will allow a narrower, targeted restriction rather than a full disabling of both models.
