Anthropic Restores Fable 5 and Launches Sonnet 5 as Default Model After U.S. Export Ban

Anthropic has restored its Fable 5 AI model globally on July 1, 2026, following an 18-day U.S. government export control ban. Simultaneously, Claude Sonnet 5 has been launched as the new default model for all free and paid Claude users. The original ban on Fable 5 was due to a bypass method discovered by Amazon researchers that could prompt the model to identify software vulnerabilities. Anthropic's investigation found this vulnerability was not unique to Fable 5, affecting several other models including GPT-5.4 and Kimi K2.7. The restored Fable 5 includes an improved safety classifier, which may lead to more false positives in some development tasks.