The US government applied export controls to Claude Fable 5 and Claude Mythos 5, and Anthropic suspended access to both for every user worldwide three days after launch. The directive barred access by foreign nationals, but with no way to verify nationality in real time the company shut the models off entirely; it said the directive arrived at 5:21pm ET that day. The government's basis was a method it believed it had found for bypassing Fable 5's safeguards. After reviewing a demonstration, Anthropic assessed it as a "narrow, non-universal jailbreak" involving asking the model to read code and identify flaws — capabilities it said were widely available from other models. The company objected that "if this standard was applied across the industry, we believe it would essentially halt all new model deployments for all frontier model providers." It was the first time the government directly halted distribution of a specific model.