Why the US restricted & then restored Anthropic’s most powerful AI models

The reversal caps an episode that began on June 12, when the Trump administration ordered Anthropic to deny the models to all foreign nationals on national security grounds. The order came at a time when Washington had been stepping up oversight of advanced AI models amid concerns that these could be misused by military intelligence in China, Russia or other countries of concern.

Since the company could not reliably separate foreign nationals from other users in real time, it had shut access to the models for everyone, Americans included.

Fable 5, released in early June, is a locked-down public version of Mythos 5, a model Anthropic had held back from wider public release over its unusually strong ability to spot vulnerabilities that hackers could exploit. Mythos 5 went only to a small set of companies and governments as part of what Anthropic calls Project Glasswing, allowing these select groups and entities to discover other potential dangerous uses or vulnerabilities in their own infrastructure.