On June 12, artificial intelligence (AI) lab Anthropic suspended access to its latest Claude models, Fable 5 and Mythos 5, which had been released three days earlier.

The move came in response to an “export control directive” from the US government prohibiting use of the models by anyone who is not a US national.

Mythos is Anthropic’s most powerful, or “frontier”, model. When first announcing the model in April, the company said it was too good at hacking to release immediately. Instead, Mythos was made available to a handful of organisations (mostly US tech corporations) to use to patch weaknesses in essential digital systems.

Fable is the same basic model, but with added safeguards meant to stop it being used for cybersecurity purposes. This is what was released to the public last week – and almost immediately shut down.

Anthropic and the Trump administration at loggerheads