Anthropic has announced its Fable 5 and Mythos 5 models will once again be available to the public as it has reached an agreement with the Commerce Department to deploy the AI models with new guardrails and classifiers meant to address jailbreaks.

In a blog posted Tuesday, Anthropic said that export controls that prevented their sale to foreign companies and individuals have been lifted after weeks of negotiation with the White House and Commerce Department. The company has also restored access to the model for U.S. users.

The export controls were put in place after the Trump administration became alarmed by a threat intelligence report from Amazon claiming to have jailbroken Fable’s cybersecurity capabilities.

On X, Secretary of Commerce Howard Lutnick appeared to confirm that the restrictions would be lifted.

“Over the past two weeks, we have worked closely with Anthropic to analyze and approve Fable 5 to ensure alignment across the US Government and strengthen America’s leadership in AI,” Lutnick wrote.

The administration levied the export controls after becoming concerned that the release of Fable 5 would lead to the model being jailbroken, giving users access to cybersecurity and other capabilities that Anthropic has said could wreak havoc on the open internet if  placed in the wrong hands. The Amazon report convinced administration officials that such jailbreaks were on the immediate horizon.

However, one oddity of the administration’s decision is that the capabilities described in the Amazon report, by all accounts, are not cutting-edge. Scanning code and breaking down how to exploit vulnerabilities for a user is already possible with existing models.

Anthropic confirmed that, saying that further testing found that equivalent and lesser models like ChatGPT 5.5, Claude Opus 4.8 and Kimi K2.7 could identify the same vulnerabilities as Fable did in the Amazon report, while a half dozen existing models were able to produce the same proof of concept code as Fable.

Crucially, Anthropic reiterated that they have yet to see a jailbreak that affects the model’s restrictions on cybersecurity and biology work, though they did call this instance “a borderline case.” Indeed, some cybersecurity professionals have publicly complained that existing safety guardrails on Fable 5 blocked many routine defensive cybersecurity work in addition to malicious use cases.

“Importantly, the reported technique did not expose any unique Mythos-level cyber capabilities,” the blog continued. “The behavior reflected a borderline case for Fable 5’s safeguards…there are some tasks that are unlikely to be dangerous but are nonetheless blocked by the safeguards out of an abundance of caution. The reported technique allowed access to one such behavior, but it only involved routine defensive cybersecurity work.”

Anthropic said it has trained new safety classifiers to target and block the behaviors described in the Amazon report and notify users when it happens, and that the new safeguards have been stress tested by the federal Center for AI Standards and Innovation. The new classifiers will block the techniques “99.9%” of the time, but Anthropic said they’re not expected to block all lower risk routine cyberdefense capabilities, just the most harmful ones.

The restrictions will likely make it even harder to use Fable 5 for defensive cybersecurity. One effect the company expects is that more “benign” requests for routine coding and debugging tasks will be flagged by the system.

Christopher Padilla, former Assistant Secretary for Commerce for export administration in the George W. Bush administration, said that while it’s “good news” the controls have ultimately been lifted, the Trump administration’s AI policy stumbles over the past two years illustrate “the risks of ad hoc, transactional policymaking.”

In a LinkedIn post, Padilla called the Trump administration’s approach chaotic and unpredictable — the opposite of the clear, consistent rules industry depends on. While Vice President J.D. Vance mocked AI safety regulations in a speech in Europe last year, the administration has quietly partnered with OpenAI and Anthropic on voluntary national security testing, especially as frontier models began showing advanced automation and cyberattack capabilities.

That national security arrangement was supposedly codified in a White House executive order last month, shaped heavily by industry boosters who feared regulatory delays would slow U.S. development. But days after Fable’s release, Commerce imposed new export controls on Anthropic’s models anyway.

Padilla called proposed AI safety regulations by the Biden administration “flawed and overly complex” but nevertheless predictable compared to the status quo. Instead of replacing those proposed regulations with their own vision, the Trump White House has been “to put it mildly, all over the place on AI policy.”

“The same BIS that stopped Fable and Mythos has a permissive policy for exporting high-end AI semiconductors to China — in exchange for a cut of the take,” said Padilla, referencing the Trump administration’s lifting of export controls on advanced AI chips. “This is not a smart way to make policy. Bad for industry competitiveness and for national security.”

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Last Friday, the Trump administration sent a shock through the tech ecosystem when the Department of Commerce levied export controls on Anthropic’s new AI model Fable 5.

Anthropic has taken steps to limit the risks around the commercial sale of its Mythos model, including declining to release it publicly, funneling it to organizations for cyber defense and developing guardrails for Fable 5 that would default its answers to older, less powerful models around sensitive topics like cybersecurity and biological warfare.

But the Trump administration was reportedly alarmed by recent reports from Amazon and another cybersecurity researcher claiming to have jailbroken Fable 5 within days of its public release, and determined that if researchers in the U.S. could jailbreak the model, so could America’s foreign adversaries.

The Commerce Department’s decision spurred Anthropic to shut off the models for all users as they attempted to convince the White House to change course.

But some cybersecurity and AI experts have sharply disagreed with the White House’s actions, saying the research has not demonstrated that anyone has been able to circumvent Fable 5’s safeguards and access the kind of dangerous new capabilities that have worried officials.

Katie Moussouris, a well-known cybersecurity expert, said Monday that Anthropic provided her with a copy of third-party research on guardrail bypass techniques for Fable 5.

According to Moussouris, the researchers asked three Claude models – Fable 5, Mythos and Claude Opus – to review batches of known, vulnerable open source code for security issues. Fable 5 initially refused the request, but the researchers were able to use “a multistep and manual process” to get Fable 5 to turn the output into automated scripts that could test patches for the vulnerability.

Third-party research since Fable 5’s release has not found ways to bypass its safeguards around hacking. The capabilities researchers have demonstrated are foundational to what makes Fable 5 and other frontier models valuable for cybersecurity defense.

“Defenders need to be able to ask AI to fix the bugs in a file, explain why the fix matters, and write tests that confirm the patch works,” she wrote. “That is not a guardrail bypass. It is the most valuable thing an AI model can do for defensive security: executing the find, fix, and test loop defenders run every day.”

Moussouris previously provided technical expertise to the Waasenaar Agreement, a voluntary multilateral security agreement around controlling exports for both munitions and dual use technology that includes the U.S. and dozens of other countries.  Based on the research she’s seen, she called placing export restrictions on all foreign sales of Fable 5 “heavy handed” and “misguided.”

Some lawmakers who in favor of higher regulations and scrutiny on the national security implications of AI were nevertheless critical of the White House decision. Senator Mark Warner, D-Va., told CyberScoop in a statement that while “there may be circumstances where restrictions on the export of frontier AI models are warranted,” those decisions must be “grounded in a transparent, risk-based process with clear rules and consistent standards.”

The Trump administration’s approach, he argued, has been the opposite, and he called for Congress to pass a statutory framework for testing and approving frontier AI models based on transparency, predictability and fairness.

“This administration has repeatedly shown a willingness to weaken export controls designed to protect our national security and maintain our technological edge over adversaries, while also making no secret of its hostility toward Anthropic,” said Warner. “That raises serious questions about whether this effort is being driven by objective national security concerns or something else.”

Anthropic said it subjected Fable 5 to 1,000 hours of testing from internal and external red team, reporting that no universal jailbreaks were found that would remove those guardrails or allow the model to access Mythos for cyber and biology work.

Moussouris is far from alone. She is one of dozens of cybersecurity experts who signed an open letter Monday calling on the Trump administration to “Free Fable.”    

The researchers say that while Mythos-class models are “quite good” at identifying and exploiting vulnerabilities in software code, they “are not uniquely good” compared to other frontier models they use every day for cybersecurity defense.

For example, despite OpenAI’s Daybreak model offering similar vulnerability discovery and patching capabilities. It was not included in the Commerce Department’s restrictions.

The researchers also note that Fable 5’s guardrails have been notoriously oversensitive compared to other frontier models used by red teamers, becoming “a source of humor in the cyber community on launch day” as IT and cyber workers reported online that they couldn’t get the model to perform basic defensive cybersecurity tasks.

The letter questions whether the issues found in the jailbreaking reports would even qualify as offensive capabilities, and note they can be reproduced in other commercial and open-source models, including GPT 5.5, Claude Opus, Claude Sonnet and Chinese models like Kimi 2.7.

“The justification for this unprecedented action was that Fable provides a unique ‘uplift’ of capabilities beyond other AI models, but AI has been finding bugs and generating working exploits at superhuman levels since last year,” they wrote.

The White House decision comes as AI companies face increasing backlash from a public that is now overwhelming calling for more robust government intervention.

A Johns Hopkins University poll in May found broad, bipartisan support for AI regulations, with 73% calling for bans on AI-generated images and video, 68% calling for labels on AI content, 75% wanting disclosure laws around when they interact with AI chatbots and 70% calling for “the right to interact with a human rather than an AI in medical, legal, educational and government settings.”

Another global survey of 18,000 people released this week found that the top four concerns most people have around AI all revolve around the tool’s ability to spread misinformation, create deepfakes to embarrass or hurt others, making it easier for criminals to hack into victim networks and helping terrorists create new weapons.

Senior reporter Tim Starks contributed reporting for this story.

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