David Sacks, co-chair of the President's Council of Advisors on Science and Technology and the administration's former AI czar, said the U.S. government warned Anthropic that Claude Fable 5 had been jailbroken and that CEO Dario Amodei refused to fix the flaw or pull the model. In a post on X on Saturday, Sacks laid out the administration's account a day after it ordered both Fable 5 and Mythos 5 disabled worldwide. Sacks said the administration issued the export control "reluctantly" after that refusal, that it wants the restriction lifted once the jailbreak is patched, and that "the ball is in Anthropic's court."

Sacks claims that a trusted partner of both Anthropic and the U.S. government, testing Fable, came forward with a jailbreak of the guardrails that separate the consumer model from the unrestricted cyber capabilities of Mythos, the model it’s built on. He said the administration asked Amodei to fix the bypass or de-deploy the model, and that Amodei declined. Anthropic instead prioritized keeping its consumer model live over safety, Sacks wrote, calling that inconsistent with the company's positioning as a safety-first lab that had itself lobbied for Mythos to be regulated as a cyberweapon.

Sacks also moved to separate the action from Anthropic's earlier clashes with the government, writing that anyone tying the export control to those disputes is wrong, and that the administration values Anthropic's technology and sees the issue as easily resolved.

A person close to the White House told the news outlet Semafor that Amazon flagged the jailbreak to the government, and that Amazon CEO Andy Jassy had been in contact with the administration about it. Amazon, which has invested billions in Anthropic and supplies much of its cloud computing, didn’t confirm the details, with a spokesperson telling Semafor that governments often seek its counsel on security risks and that it doesn’t discuss those conversations.

This isn’t the first time Mythos access has leaked; it happened back in April when unauthorized third parties reached the restricted model using information from a data breach. Anthropic’s public position is that the bypass is narrow and non-universal, that it amounts to asking the model to read a codebase and identify software flaws, and that the same result can be produced on other public models, including OpenAI's GPT-5.5. The company has stated that it disagrees with the notion that a narrow jailbreak should necessitate the recall of a model used by hundreds of millions of people. Sacks rejects this, arguing that a bypass enabling operation of a cyberweapon is difficult to define as anything other than serious.

Semafor, citing a person familiar with the matter, says that the White House acted partly over suspicion that a China-linked group had accessed Mythos, raising the prospect of the model being reverse-engineered or distilled. An Anthropic spokesperson told the outlet that the White House "didn’t raise Chinese access to Mythos in its conversations around the Fable jailbreak," and that Anthropic blocks access to its products from inside China.

Anthropic is separately suing the Pentagon following an impasse over the use of its models in autonomous weapons, and has opposed federal efforts to preempt state AI regulation.

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Luke James is a freelance writer and journalist.  Although his background is in legal, he has a personal interest in all things tech, especially hardware and microelectronics, and anything regulatory.