Anthropic announced the redeployment of Claude Fable 5 and Mythos 5 after US export controls were lifted on June 30, 2026. The models had been temporarily restricted following the discovery of a jailbreak technique that could help identify software vulnerabilities. Anthropic developed an improved safety classifier blocking the reported technique in over 99% of cases and partnered with major tech companies to establish an industry framework for assessing AI jailbreak severity.
