Anthropic's Fable 5 had the shortest honeymoon in AI history

Anthropic Launch Blog

On June 9, Anthropic launched Claude Fable 5 — its most capable public model yet. By June 12, the US Department of Commerce had yanked it offline globally.

Fable 5 was supposed to be Anthropic's flagship: advanced reasoning chops, scientific-grade capabilities, the works. A restricted biodefense variant called Mythos 5 rolled out to vetted partners through Project Glasswing. Then a hacker known as "Pliny the Liberator" published a jailbreak demonstrating how to extract chemical synthesis instructions and cyber exploit details from the model. Cue the national security alarm bells.

The Trump administration invoked emergency export control authorities and pulled both models mid-launch. Foreign developers lost API access overnight with no warning. Enterprise teams worldwide are now quietly pivoting to local open-source alternatives. Anthropic is challenging the Pentagon's "supply chain risk" designation, arguing First Amendment retaliation — but the damage is already done. (The irony: Anthropic's valuation just hit $965 billion ahead of a rumored IPO.)