Chronicle/Policy & standards

US lifts export controls on Fable 5 and Mythos 5; Anthropic redeploys with new cyber classifier

PolicyRegulationSignificance assistant-drafted

Anthropic announced that export controls on Fable 5 and Mythos 5 had been lifted and that Fable 5 would be redeployed globally from July 1, 2026 with an improved safety classifier. Anthropic says the classifier blocks the technique described in an Amazon report in over 99% of cases and that CAISI researchers tested its prior and new safeguards. Mythos 5 access was restored for a set of US organizations after government approval on June 26.

Why it matters

It shows the conditions, including government testing of safeguards, under which a suspended cyber-capable model was allowed back.

Key facts

As stated in the sources, with where to find them.

  • Anthropic reports the new classifier blocks the technique described in the Amazon report in over 99% of cases.Updated safeguards section
  • The Amazon report described prompting the model to identify software vulnerabilities, and in one case to produce code demonstrating exploitation.Background section
  • Coordination involved ONCD, OSTP, Treasury, Commerce (including CAISI) and national security agencies; Mythos 5 access restored for some US organizations after approval on June 26.Government coordination; Mythos 5 section

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