Anthropic keeps Fable 5 and Mythos 5 offline as US talks continue

Anthropic's newest model incident is now a government-access dispute. The company said the US government issued an export-control directive requiring Anthropic to suspend access to Claude Fable 5 and Claude Mythos 5 for any foreign national, including Anthropic employees; Anthropic said the practical result was disabling both models for all customers. Access to other Anthropic models is not affected. 1

Fable 5 and Mythos 5 had launched only days earlier. Anthropic described Fable 5 as a Mythos-class model made safe for general use, and Mythos 5 as the same underlying model with some safeguards lifted for a smaller group of cyberdefenders and infrastructure providers through Project Glasswing. 2

The directive turns that launch into a live policy test. Anthropic said the government cited national-security authorities but did not give specific written details of the concern. The company said its understanding is that the concern involves a narrow, non-universal jailbreak that asks the model to inspect a codebase and identify software flaws. 1

Anthropic is complying, but it is also challenging the standard behind the order. The company said it reviewed what it believes is the underlying report and concluded that the demonstrated capability is also available from other public models, including OpenAI's GPT-5.5. 1

The sharper claim is procedural: Anthropic said it supports a government power to block unsafe deployments, but only through a process that is transparent, fair, clear, and grounded in technical facts. It said this action does not meet that bar. 1

Talks are still active. The Wall Street Journal reported on June 17 that President Donald Trump said negotiations with Anthropic over restoring access were "going fine" after a G7 lunch that included Anthropic CEO Dario Amodei and other AI executives. 3

The immediate customer signal is simple: Fable 5 and Mythos 5 remain the affected products, while the rest of Anthropic's model line stays available. The broader signal is less settled. A frontier-model launch can now be pulled into export-control policy after release, and Anthropic is asking whether that intervention can be tied to a clearer technical threshold before access is restored.