Anthropic's Claude Mythos 5 Gets the Green Light, But Fable 5 Is Still in AI Detention 🗝️

The US Commerce Department on Friday rescinded its export block on Anthropic's Claude Mythos 5, clearing the frontier model for release to more than 100 US institutions listed in Annex A of a letter from Commerce Secretary Howard Lutnick to Anthropic compute chief Tom Brown. "I have determined that appropriate safeguards are in place to permit certain trusted partners to access the Claude Mythos 5 Model," Lutnick wrote, ending a two-week standoff between the Trump administration and Anthropic and reversing controls imposed earlier this month that had forced both Mythos 5 and the consumer-focused Fable 5 offline.

The reversal followed the intervention of senior Anthropic staff who traveled to Washington to meet administration officials during the dispute, according to CNBC. The original block was triggered after Amazon, one of Anthropic's largest investors, warned that Fable 5 could be jailbroken for harmful use. Until the block, Mythos 5 operated inside Project Glasswing, a vulnerability-hunting program spanning roughly 150 organizations across more than 15 countries, where it had identified flaws in classified systems within hours of government testing.

Fable 5, which had been open to any subscriber before the shutdown and briefly ranked as the most powerful AI tool publicly available, remains offline, though people familiar with the talks said its release is advancing on an unspecified timeline. The episode is crystallizing into a new gatekeeping framework built around a June 2 executive order that created a voluntary channel for federal review of frontier models, allowing developers to submit systems for a cyber check up to 30 days before release.

OpenAI moved along the same track on Friday, restricting its most powerful GPT-5.6 tier, Sol, to about 20 government-approved partners while sending the weaker Terra and Luna versions to the public. Concerns over Chinese access had driven the initial controls, with reporting linking the alarm to South Korean carrier SK Telecom, which joined Glasswing in early June before losing access; SK Telecom has denied any China ties. Dozens of cybersecurity leaders, including former Facebook security chief Alex Stamos and signatories from Nvidia, Adobe, and Zoom, pressed the administration in an open letter to drop the restrictions, leaving Fable 5's clearance decision to be settled in the days ahead.