Anthropic said it will begin restoring global access to its Claude Fable 5 and Claude Mythos 5 models, after the US Department of Commerce lifted export controls that had forced the company to suspend both models for all users worldwide since mid-June. The company confirmed the development in a blog post, saying it was 'grateful' to users 'for their patience, and to everyone who worked with us on redeploying the models,' according to a statement posted on X.
The export control directive that triggered the shutdown
Anthropic said the US government had applied export controls to Fable 5 and Mythos 5 on June 12, requiring the company to restrict access to foreign nationals, whether inside or outside the United States. Because the directive took effect immediately and Anthropic had no reliable way to verify user nationality in real time, it suspended access to both models for all users globally as a precaution.
The company said the directive followed a government review of a report in which Amazon researchers had found a way to bypass Fable 5's safeguards by prompting it to identify software vulnerabilities, with the model in one instance producing code demonstrating how a vulnerability could be exploited.
Anthropic's response and new safeguards
Anthropic said its own testing found that less capable models, including Claude Opus 4.8, GPT-5.5 and Kimi K2.7, could identify the same vulnerabilities flagged in the Amazon report, and that the specific exploit demonstration could be reproduced by a wide range of existing models. The company said the reported technique did not expose "any unique Mythos-level cyber capabilities" and instead reflected a borderline case within Fable 5's built-in safety margins.
Working with the US government, Anthropic said it trained an improved safety classifier that now blocks the specific technique described in the Amazon report in more than 99 percent of cases. Users whose requests are blocked will be redirected to Claude Opus 4.8, the company said, adding that researchers from the Commerce Department's Center for AI Standards and Innovation had tested the new and prior safeguards and found them "extraordinarily strong."
Rollout timeline for Fable 5 and Mythos 5
Fable 5 will be available from July 1 to users globally across the Claude Platform, Claude.ai, Claude Code and Claude Cowork, Anthropic said. For Pro, Max, Team and select Enterprise plans, the model will be included for up to 50 percent of weekly usage limits through July 7, after which access will run through usage credits. The company said it would restore access on AWS, Google Cloud and Microsoft Foundry "as quickly as possible."
Access to Mythos 5 has also been restored for a set of US organisations following government approval on June 26, Anthropic said, adding that it continues to coordinate with the government to expand access to the broader set of domestic and international partners under its Project Glasswing programme.
