Anthropic began restoring global access to its Claude Fable 5 model on Thursday, after the United States government lifted export controls that had forced the company to suspend the model worldwide since June 12.
In a blog post, Anthropic said the export controls on Fable 5 and its more capable counterpart, Claude Mythos 5, were applied on June 12 after the government learnt of a report by Amazon researchers who had found a way to bypass Fable 5's safeguards, prompting it to identify software vulnerabilities and, in one case, produce code demonstrating how the vulnerability could be exploited.
Because the restriction required Anthropic to verify users' nationality in real time, which it had no reliable way to do, the company suspended access to both models entirely.
The company said its testing showed several less capable models, including Claude Opus 4.8, GPT-5.5 and Kimi K2.7, could identify the same vulnerabilities and reproduce the same exploit demonstration as Fable 5, and that the bypass did not expose any unique capabilities specific to Mythos 5.
Anthropic said it had since trained an improved safety classifier, tested and endorsed by the US Department of Commerce's Center for AI Standards and Innovation, that blocks the reported technique in more than 99 per cent of cases.
Fable 5 became available again from Thursday across the Claude Platform, Claude.ai, Claude Code and Claude Cowork, with the company saying it would restore access on AWS, Google Cloud and Microsoft Foundry "as quickly as possible."
ALSO READ: US Lifts Export Controls On Anthropic's Claude Fable 5 And Mythos 5
It added that they had also restored Mythos 5 access for a set of US organisations following government approval on June 26, and continues to work on expanding access to other domestic and international partners under its Project Glasswing programme.
The company said it is now working with Amazon, Microsoft, Google and other Glasswing partners to develop a shared industry framework for assessing the severity of AI jailbreaks, and is deepening collaboration with the US government on pre-release testing, information sharing and joint research on frontier AI security.
ALSO READ: Anthropic's Mythos 5 AI Model Cleared By US For Wider Use
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