US Gov asks Anthropic to ban 'foreign national' access to Fable, Mythos

Anthropic has suspended access to its two most capable AI models, Fable 5 and Mythos 5, for all users worldwide after the US government issued an export control directive ordering the company to block access by any foreign national.

US Gov: bar 'foreign national' access to Fable 5

The directive, which Anthropic says it received at 5:21pm ET on June 12, cites "national security" authorities and bars access to both models by foreign nationals inside or outside the United States, including Anthropic's own foreign-national employees.

The order's net effect, the company says, is that it must disable both models for all customers to comply. All other Anthropic models, including Claude Opus 4.8, are unaffected.

The timing is awkward. Anthropic began rolling out Fable 5 on June 9, free to all Pro, Max, and Enterprise customers through June 22. The model handed to millions for free three days ago is now offline for everyone.

Claude Fable 5 'currently unavailable' (BleepingComputer)

Fable 5 is the safeguarded sibling of Mythos 5. Both share the same underlying model, but Fable adds the safeguards.

Fable blocks or diverts sensitive cybersecurity, biology, and chemistry queries, while the unrestricted Mythos 5 goes only to vetted government cyberdefenders and life sciences partners.

In a developer notice, Anthropic said new sessions would fall back to a user's default model or Opus 4.8, existing Fable 5 sessions would end with an error, and Platform requests to Fable 5 would also fail. It told integrators to migrate to other models.

Anthropic's read is that the order stems from a reported way to jailbreak Fable 5. It says it reviewed a demo and found only minor, already-known bugs, the kind other publicly-available models are able to discover without any bypass.

"To date, the government has only given us verbal evidence of a potential narrow, non-universal jailbreak, which essentially consists of asking the model to read a specific codebase and fix any software flaws," states Anthropic.

"Our understanding is that one potential jailbreak was shared with the government."

"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."

"If this standard was applied across the industry, we believe it would essentially halt all new model deployments for all frontier model providers."

The company says the capability is widely available elsewhere, pointing to OpenAI's GPT-5.5, and is used by defenders every day.

Anthropic maintains the order is a misunderstanding and says it is working to restore access, while promising more details within 24 hours.