US removes curbs on Anthropic's latest Fable and Mythos AI models

Anthropic said that the US Commerce Department lifted export controls on its most ⁠advanced Fable and ⁠Mythos AI models, less than three weeks after the company was ordered to suspend their access over national security risks.

Washington has stepped up oversight of new model releases to identify potential threats amid concerns that advanced AI models could be misused by military intelligence in China, Russia or other countries of concern.

A June 12 order requiring Anthropic to immediately restrict access for Mythos 5 and Fable 5 to foreign nationals prompted the ‌company to disable both models for all users as there was no way to verify nationality in real ‌time.

Last ‌week, the US government allowed the company to release Mythos 5 but only to some "trusted" US organisations.

The ‌model — designed to detect cyber security vulnerabilities — had earlier been made available to a broader group of companies ⁠as part of its Glasswing project.

Anthropic said that all export controls on the models have now been lifted after the implementation of safeguards.

It is working with the US government to expand access to Mythos 5 to the broader set of domestic and international partners in the Glasswing program, it said in a blog post.

Fable 5, which is intended for the general public and has stronger safeguards, will be ​available from Wednesday.

Anthropic also said it was deepening its collaboration with the US government, giving designated government partners expanded early access to ⁠both its models.

It is also working with Amazon, Microsoft, Google and other Glasswing partners to develop shared common standards to assess and fix potential AI jailbreaks (techniques that bypass safeguards), including a system to rank the severity of such jailbreaks.

A letter to Anthropic from US Commerce secretary Howard Lutnick that was seen by Reuters said Anthropic had agreed to work diligently with the US government on protocols for Mythos, Fable and future models and to inform the US government of any malicious activity.

Lutnick, however, said that the department "reserves the right to reevaluate the decisions made in this letter and the necessity of reimposing a license requirement, should circumstances change or should Anthropic fail to adhere to its commitments".

Anthropic said the June 12 export-control order followed Amazon researchers reporting a way to bypass Fable 5's safeguards, allowing the model to identify software vulnerabilities and, in one case, generate code ​demonstrating how one vulnerability could be exploited.

Anthropic said it has now implemented a new ⁠safeguard that blocks the behavior described in the report.

Any blocked request will instead be sent to its Opus ⁠4.8 model, and Anthropic acknowledged that although this would be frustrating for users, the tradeoff was made in the interest of making the model's other capabilities widely available.

Anthropic warned that it was "probably impossible" ​to make any AI model fully robust to jailbreaks and noted the potential for the development of a universal jailbreak that would be able to unblock "an entire ‌class of harmful behaviours."

"There will ⁠be many minor jailbreaks, some narrow harmful ones, and although no universal jailbreaks for Fable 5 have been discovered at the time of writing, expert safety researchers continue to red-team it," the company said.

Isaac Harris, executive director of the Frontier Security Institute, a nonprofit focused on AI and national security, said there now appears to be a process for standards of the US ‌models.

But he added: "There's still a question mark as to how equivalently dangerous capabilities coming from China with less guardrails will be handled by the administration in the US market."

OpenAI has also faced restrictions

Increased scrutiny of AI models this month began with US President Donald Trump's signing of an executive order establishing a voluntary framework for AI developers to offer "covered frontier models" to the US government for up to 30 days before releasing them to ​trusted partners.

Like Anthropic, rival OpenAI has also faced restrictions. It said last week that it had delayed a full public launch of GPT-5.6 at the US government's request, limiting its access to a small group of vetted partners.

Anthropic's relationship with the US government has been particularly tense.

The Pentagon earlier this year designated the company a "supply-chain risk", preventing contractors from using Anthropic's AI ‌when working for the US ⁠military, after the company refused to allow its models to ​be used for mass domestic surveillance or fully autonomous weapons systems.

Both OpenAI and Anthropic have confidentially filed for US initial public offerings.