Anthropic removes access to Claude Fable 5 and Mythos 5, here is why
Follow UsAnthropic launched Claude Fable 5 and Mythos 5 earlier this week.
Anthropic has suddenly removed access to both AI models for all users.
The decision follows a legal order from the US government.
Anthropic launched Claude Fable 5, the first Mythos-class AI model designed for general use, earlier this week. Alongside it, the company also introduced Claude Mythos 5, an updated version of its restricted AI model. Now, just a few days after launch, Anthropic has suddenly removed access to both AI models for all users. The decision follows a legal order from the US government, citing national security authorities.
SurveyIn a blogpost, Anthropic said it received an export control directive from the government. The order required the company to stop access to Fable 5 and Mythos 5 for all foreign nationals, both inside and outside the US. “The net effect of this order is that we must abruptly disable Fable 5 and Mythos 5 for all our customers to ensure compliance,” the AI company said.
The letter offered no details about the alleged national security concern. However, Anthropic believes the government may have found a technique that bypasses or jailbreaks Fable 5.
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Anthropic further stated that, so far, the government has offered only verbal evidence of a narrow, non-universal jailbreak that appears to involve asking the model to analyse a specific codebase and fix software flaws. Anthropic explained that it reviewed the report and found that the results were not unique to Fable 5 and that other publicly available AI models (including OpenAI GPT-5.5) can already do similar tasks.
“We have not even received a disclosure of a concerning non-universal potential jailbreak that led to a harmful result. The potential jailbreaks that have been disclosed to us are either entirely benign responses or are minor findings that provide no Mythos-specific uplift,” Anthropic said.
Anthropic also defended the safety systems built into Fable 5. Before launch, the company worked with government agencies, outside security researchers, and internal teams to test the model for possible misuse. According to the company, no testers found a broad method that could fully bypass the model’s protections. Anthropic also admitted that no AI model today is likely to be perfectly protected against jailbreak attempts.
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Despite following the government order, Anthropic said it disagrees with the decision. “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 said. “We apologise for this disruption to our customers. We believe this is a misunderstanding and are working to restore access as soon as possible.”
