Anthropic suspends Fable and Mythos systems "for all users" after US government claims jailbreak risk

Anthropic has suspended most of its advanced AI models just days after the company made them public, after sanctions were imposed by the Trump administration.

On Friday, Anthropic models Fable and Mythos were hit with export controls by the Department of Commerce, barring foreign nationals from using either model. In response, Anthropic has suspended both systems for all users.

In a statement posted on its website, Anthropic said that it was complying with the government's legal directive and removing access to Fable 5 and Mythos 5 for all users. But it disagreed with the government's reasoning as it only offered verbal evidence of a "potential narrow, non-universal jailbreak", according to Anthropic.

For AI systems, a jailbreak is a technique used to manipulate an AI model into bypassing its built-in safeguards, guardrails, and content filters. An AI chatbot, for example, which is designed to assist, has vulnerabilities that can be exploited by malicious actors and forced to do things it was specifically programmed not to.

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Anthropic believes the jailbreak method claimed to have been found in Fable and or Mythos is widely available in other models, such as OpenAI's GPT-5.5, and is used daily by the security teams that keep it safe.

"We disagree that the finding of a narrow potential jailbreak should be a cause for recalling a commercial model deployed to hundreds of millions of people," the statement reads. "If this standard was applied across the industry, we believe it would essentially halt all new model deployments for all frontier model providers."

"Perfect" jailbreak resistance, according to Anthropic, is not currently possible for any model provider. And that every safeguard used in the industry is vulnerable to non-universal jailbreaks. The company added that it was likely that universal jailbreaks would eventually be found in the future, a point it stressed when it first released Fable 5.

Pentagon, AWS, and Anthropic

The sanctions on Anthropic come not long after the Pentagon named the company as a supply-chain risk to national security. A number of senior government figures publicly clashed with Anthropic's leadership over issues including AI regulation and the use of Anthropic's technology in domestic surveillance and autonomous weapons.

The specific directive, however, followed a report by Amazon researchers who identified the potential jailbreak in Fable. Reportedly, Amazon first shared its findings with Anthropic. CEO Andy Jassy is also said to have discussed the issue with US officials, raising broader concerns about frontier-model capabilities rather than issues focused specifically on Anthropic.