US government forces Anthropic to disable Claude Fable 5 and Mythos 5 for all customers worldwide

The US government has ordered Anthropic to shut down global access to Fable 5 and Mythos 5, citing alleged jailbreak risks. Anthropic is complying but pushing back publicly: the vulnerabilities are minor and exist in competing models like GPT-5.5, the company says, an ironic turn after the company spent months hyping the cybersecurity risks of its own Mythos class.

Anthropic warns the move could set a precedent that halts all frontier deployments.