anthropic has paused access to Claude Fable 5 and Claude Mythos 5 for all users following a US government directive to restrict access to foreign nationals. The company explained that the order requires them to disable both models completely to comply with regulations.
What caused 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 knows of a method to bypass or “jailbreak” Fable 5.
He also mentioned reviewing a demonstration of this technique. According to Anthropic, the exposed vulnerabilities are “relatively simple” and other publicly available models can also discover them without needing to bypass them.
“We reviewed a demonstration of this specific technique used to identify a small number of previously known minor vulnerabilities,” Anthropic explained. “All of these vulnerabilities appear to be relatively simple, and we have found that other publicly available models can also discover them without needing to avoid them.”
Customers using the Pro, Max, and Enterprise plans who accessed Fable 5 during its free preview period will no longer be able to 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 become available again or what conditions must be met to lift the suspension. Other Claude models, including the Claude Opus 4.8, remain available.
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 called Anthropic a “supply chain risk.”
This designation, typically reserved for adversary countries, marks the first time a U.S. company has received it, indicating that the tool or service is not considered secure enough for government use.
Anthropic is suing the Pentagon over the designation, and a US judge has ruled that the Pentagon directive is unenforceable while the lawsuit is ongoing. As a result, government agencies and organizations working with the U.S. military may continue to use Anthropic products temporarily.
The BBC reported that it has contacted the US Department of Commerce for comment on the suspension of Fable 5.
Anthropic previously stated that Fable 5 exceeds the capabilities of any model the company has made available to the public, and that the Mythos architecture is described as “too powerful to release” without substantial safeguards.
The Mythos program was limited to selecting trusted partners through Project Glasswing for cybersecurity research ahead of the broader release of Fable 5 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 restored.
Anthropic is suing the Pentagon over the designation. A US judge ruled that the Pentagon directive is unenforceable while the lawsuit continues, meaning government agencies and organizations working with the US military can still use Anthropic products in the meantime.
The BBC reported that it has approached the US Department of Commerce for comment on Fable 5’s suspension.
Anthropic previously described Fable 5 as exceeding the capabilities of any model the company had made available to the public, 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 ahead of the broader release of Fable 5 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 be made available again.
