Anthropic Reportedly Finishes Training Successor to Suspended Mythos 5 Model

Anthropic has reportedly finished training a more capable Mythos successor, according to AI watcher Andrew Curran. The company has not confirmed the model’s existence, name, or capabilities.

Curran said the system could ship as Mythos 5.1 or Mythos 6, or stay internal. His report came nine days after US export controls forced Anthropic to suspend Mythos 5 and Fable 5.

Mythos Successor Emerges from Training

Curran describes the supposed new system as stronger than Mythos 5. However, he stressed uncertainty over its name and whether Anthropic would release it at all.

“A new, more capable version of Mythos has emerged from training. I don’t know whether it will be called Mythos 5.1 or Mythos 6, or if Anthropic will keep it internal to accelerate further development…” Curran wrote.

Anthropic released Mythos 5 and Fable 5 on June 9 and lost them to the directive three days later. Several still expect an iterative upgrade, partly because the model suspension order limits today’s lineup.

Fable 5 ships with heavy safeguards for public use. Mythos 5 runs with fewer security restrictions through Project Glasswing, the firm’s vetted cybersecurity program.

Anthropic says about 50 partners have used early Mythos models to find more than 10,000 high- or critical-severity software flaws.

Why the Suspension Does Not Stop Development

Commerce Secretary Howard Lutnick sent the directive to Anthropic chief Dario Amodei on June 12, citing national security.

A bipartisan group of lawmakers is pressing Commerce Secretary Howard Lutnick to explain the legal and technical rationales behind the decision to impose export controls on Anthropic’s new models.@Dareasmunhoz has the story:https://t.co/Oou0YQT9zV pic.twitter.com/PdMvp0U9N5

— Punchbowl News (@PunchbowlNews) June 18, 2026

It barred every foreign national, including Anthropic’s own foreign-born staff, so the firm disabled both models worldwide.

The government flagged a method for bypassing Fable 5’s safeguards. Anthropic reviewed the demonstration, called it narrow, and warned the same standard would halt new model launches industrywide.

It is still working to reverse the export controls.

Subscribe to our YouTube channel to watch leaders and journalists provide expert insights

The order followed a reported Amazon warning to officials. Amazon has committed up to $25 billion to Anthropic.

Even so, it reportedly told the administration its researchers used Fable 5 to surface attack-ready information.

The clash later drew comments from Donald Trump and a public defense from Amodei.

Curran argued that halting deployment does little to slow progress and may even speed it up by freeing resources.

He pointed to open-weights rivals such as Z.ai’s GLM-5.2, which matches far larger closed models on coding tasks at a fraction of the cost.

The successor’s path stays uncertain. Anthropic shipping it publicly, restricting it to Glasswing, or keeping it internal could reshape the AI race.

The company continues to seek restored access for both suspended models and has not addressed latest developments publicly.