Anthropic has disabled access to Claude Mythos 5 and Claude Fable 5 for all customers after receiving an export control directive from the US government, which cited national security concerns around the two newly launched AI models.
The move comes just days after Anthropic introduced both models, with Mythos 5 positioned for restricted security research through Project Glasswing and Fable 5 made available more widely with added safeguards to reduce misuse.
Commerce Secretary Howard Lutnick sent a letter to Anthropic CEO Dario Amodei stating that both models would face export controls outside the US and for foreign persons inside the country.
Anthropic says other Claude models remain available
Anthropic said it received the directive and had to “abruptly disable” both models to comply, while confirming that access to all other Claude models remains unaffected.
“The US government, citing national security authorities, has issued an export control directive to suspend all access to Fable 5 and Mythos 5 by any foreign national, whether inside or outside the United States, including foreign national Anthropic employees. The net effect of this order is that we must abruptly disable Fable 5 and Mythos 5 for all our customers to ensure compliance,” Anthropic said.
The company said the government did not share specific details about the national security concern, though Anthropic believes the action relates to a reported jailbreak method involving Fable 5.
Anthropic argued that the demonstrated technique found only a small number of previously known, minor vulnerabilities and said similar results can be achieved through other public models, including OpenAI’s GPT-5.5.
For users, new Claude sessions will now run on the selected default model or Opus 4.8, while existing Fable 5 sessions will end with an error.
