Anthropic Enables the Redeployment of Claude Fable 5 and Mythos 5

The U.S. government has lifted export controls on Anthropic's most advanced AI models, Claude Fable 5 and Mythos 5.

"Over the past [few] weeks, we have worked closely with Anthropic to analyze and approve Fable 5 to ensure alignment across the US Government and strengthen America's leadership in AI," said commerce secretary Howard Lutnick in a post on X.

This move comes after the government issued the export control directive on June 12 after becoming aware of a report in which Amazon researchers had found a method of bypassing Fable 5’s safeguards: prompting it so that it identified several software vulnerabilities. In one case, the model produced code demonstrating how the relevant vulnerability could be exploited, Anthropic said.

Working closely with the government, Anthropic trained an improved safety classifier that targets and blocks the behavior described in the report. Users will be notified if a request to Fable 5 is blocked, and the request will instead be sent to Opus 4.8.

The new classifier means that the specific technique described in the Amazon report is blocked in over 99% of cases. In a very small fraction of cases the model may provide information that isn’t detailed enough to help a cyberattacker, the company said.

Now, Fable 5 is available to users globally on the Claude Platform, Claude.ai, Claude Code, and Claude Cowork. For Pro, Max, Team, and select Enterprise plans, Fable 5 will be included for up to 50% of weekly usage limits through July 7, after which it will be available via usage credits. The company is working to re-enable access on AWS, Google Cloud, and Microsoft Foundry as quickly as possible.

Access to Mythos 5 is available for a selection of U.S. organizations, following the US government’s approval. Anthropic will continue to coordinate with the government to expand access to the broader set of domestic and international partners in the Glasswing program.

For more information about this news, visit www.anthropic.com.

Anthropic Prompted to Take Down Access to Fable 5 and Mythos 5 by the U.S. Government

After Anthropic debuted Fable 5 and Mythos 5 to general and select organizations last week, the U.S. government 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.

15 Jun 2026