Anthropic has paused access to Claude Fable 5 and Claude Mythos 5 for all users following a directive from the US government to restrict access for foreign nationals. The company explained that the order requires them to disable both models completely to stay compliant.
What Triggered the Suspension of Fable 5 and Mythos 5, and What It Means for Users
Anthropic stated that US national security authorities have not publicly identified specific concerns. The company claimed that the government is aware of a method to bypass or “jailbreak” Fable 5.
It also mentioned reviewing a demonstration of this technique. According to Anthropic, the vulnerabilities exposed are “relatively simple,” and other publicly available models can also discover them without needing a bypass.
“We reviewed a demonstration of this specific technique used to identify a small number of previously known, minor vulnerabilities,” Anthropic explained. “These vulnerabilities all appear to be relatively simple, and we have found that other publicly available models can discover them as well without requiring a bypass.”
Customers using Pro, Max, and Enterprise plans who accessed Fable 5 during its free preview period can no longer use the model. The Mythos 5 access program for vetted partners is also affected.
Anthropic has not provided a timeline for when Fable 5 or Mythos 5 might be available again or what conditions need to be met to lift the suspension. Other Claude models, including Claude Opus 4.8, remain accessible.
Wider Tension Between Anthropic and the Trump Administration
The suspension comes amid an ongoing dispute between Anthropic and the Trump administration. President Donald Trump has publicly criticized the company, and former US Defense Secretary Pete Hegseth labeled Anthropic a “supply chain risk.”
This designation, typically reserved for adversarial countries, marks the first time a US company has received it, indicating that the tool or service is not deemed secure enough for government use.
Anthropic is suing the Pentagon over the designation, and a US judge has ruled that the Pentagon’s directive cannot be enforced while the lawsuit is ongoing. As a result, government agencies and organizations working with the US military can continue using Anthropic products temporarily.
The BBC reported that it has contacted the US Department of Commerce for comment on the Fable 5 suspension.
Anthropic previously stated that Fable 5 surpasses the capabilities of any model the company has made publicly available, with the Mythos architecture described as “too powerful to release” without substantial safeguards.
The Mythos program was limited to select trusted partners through Project Glasswing for cybersecurity research before Fable 5’s broader release earlier this week.
Anthropic has not announced any modifications it plans to make to address the government’s concerns before Fable 5 and Mythos 5 can be reinstated.
Anthropic is suing the Pentagon over the designation. A US judge has ruled the Pentagon’s directive cannot be enforced while the lawsuit continues, meaning government agencies and organizations working with the US military can still use Anthropic products in the interim.
The BBC reported it has approached the US Department of Commerce for comment on the Fable 5 suspension.
Anthropic previously described Fable 5 as exceeding the capabilities of any model the company had made generally available, with the underlying Mythos architecture characterized by Anthropic as “too powerful to release” without significant safeguards.
The Mythos program was restricted to a small number of trusted partners through Project Glasswing for cybersecurity research before Fable 5’s broader release earlier this week.
Anthropic has not announced what changes, if any, will be made to address the government’s concerns before Fable 5 and Mythos 5 can return to availability.
