Anthropic Blocks Public Access to Fable 5 and Mythos 5

Anthropic has taken the drastic step of blocking all public access to its most advanced AI models—Claude Fable 5 and Mythos 5—following a U.S. government export control directive citing national security concerns. The move affects both domestic and foreign users and has significant implications for enterprise customers who relied on these models. The government order, issued under export control regulations, restricts access to the top-tier models by foreign nationals and entities deemed a risk to national security. Anthropic complied by immediately shutting down public APIs and user interfaces for both models, even for users within the United States, to ensure full compliance. "This is an unprecedented action," said Dr. Sarah Kim, an AI policy analyst. "We’ve seen restrictions on AI hardware exports, but blocking access to software models themselves is new. It signals that the government views certain AI capabilities as strategic assets that must be protected." Enterprise customers who had integrated Fable 5 or Mythos 5 into their workflows are now scrambling to find alternatives. Many had built critical applications around these models’ advanced reasoning and creative capabilities. Anthropic has offered limited support for migration to its less powerful models, but some businesses face significant disruptions. The company has not disclosed the specific national security concerns that prompted the directive, but experts speculate it relates to the models’ potential use in cybersecurity, cryptography, or disinformation campaigns. Anthropic has stated it is working with government officials to develop a framework for controlled access, possibly including enhanced vetting of users. The situation highlights the growing tension between AI advancement and national security, as governments worldwide grapple with how to regulate powerful AI systems without stifling innovation. For now, Anthropic’s top-tier models remain locked behind government restrictions, leaving the industry to watch closely for what comes next.