Statement on U.S. Government Directive to Suspend Access to Fable 5 and Mythos 5

The U.S. government, citing national security authority, has issued export control guidance directing the suspension of all access to Fable 5 and Mythos 5 for foreign nationals (including Anthropic employees). In response, Anthropic has decided to immediately suspend service for these models in order to comply with the directive. However, all other Anthropic models are not affected by this action.

The government has cited the discovery of a jailbreaking method for Fable 5 as the basis for its directive, but has not disclosed specific security concerns. According to Anthropic's own review, the vulnerability discovered is minor and already known, and it has been determined that other publicly available models—including OpenAI's GPT-5.5—can perform at a similar level without any separate jailbreak.

Anthropic has maintained the following security strategies:

• Defense in depth: A multi-layered defense strategy designed to narrow the scope of jailbreak attempts or increase their cost
• Red-teaming: Thousands of hours of pre-release testing conducted together with government agencies and third-party organizations
• Data retention: A policy of retaining customer data for 30 days to detect and mitigate jailbreak attacks

While Anthropic is complying with the government's legal directive and suspending service, the company has stated that it disagrees with the decision to restrict access to a commercial model based solely on the discovery of a vulnerability.