Mythos 5, pulled in three days

On June 9 Anthropic took its top tier public for the first time, in two configurations of one model. Fable 5 is the general release, with extra refusals on bioweapon and offensive-cyber requests that drop it back to the older Opus in under 5% of sessions. Mythos 5 is the same model with those guardrails lifted, sold only to vetted cyber-defense and infrastructure partners. Both landed at $10 and $50 per million words in and out — less than half what the partner-only preview cost in April.

We cannot tell foreign from domestic users in real time. — Anthropic

Three days later it was gone. On June 12 the US Commerce Department ordered access cut for any foreign national, inside or outside the country, after someone demonstrated a way around Fable 5's cyber blocks. Anthropic says it cannot tell foreign from domestic users in real time, so a directive aimed at some users took the model away from all of them — including the company's own foreign-national staff. It complied within days while publicly disputing the reasoning, noting that other public models hit the same flaws with no bypass at all.

The benchmarks barely moved from the spring preview, and the price was cut in half; the real event is the precedent. A US export rule can now reach into a deployed frontier model and switch it off everywhere at once, and the lever it pulled was a single jailbreak of the safeguards that were supposed to make a public release safe. Every enterprise that wired Fable 5 into production over those three days had to rip it back out.