Anthropic said in October 2026 that Zhipu switched from distilling Claude Fable 5 to an older Claude model and another lab's model after Claude Fable 5's cyber safeguards degraded its attacks

Anthropic describes new defenses against illicit distillation of Claude, including preserved thinking, a two-stage classifier, and account bans, which cut extracted reasoning tokens 10-100x. It argues distillation threatens national security and urges all developers and platforms to act.