Anthropic releases Claude Fable 5 and Claude Mythos 5

Background

Mythos 5 was first deployed through Project Glasswing, which Anthropic carried out in collaboration with the US government. ^[1]

What happened

On 9 June 2026 Anthropic released Claude Fable 5, which it described as its first Mythos-class model for general use. It also released Claude Mythos 5, the same model with some safeguards lifted for vetted partners. ^[1]

Both models were priced at $10 per million input tokens and $50 per million output tokens. ^[1]

Key details

Requests about cybersecurity, biology and chemistry, or distillation fall back to Claude Opus 4.8. ^[1]

Subscription plans included Fable 5 at no extra cost until 22 June. After that date, usage credits were required. ^[1]

A trusted-access programme gives wider capabilities only to users a company has checked. Distillation is the practice of training a smaller model on the outputs of a larger one, which is why some requests of that kind are restricted. Export controls are government rules that limit the sale or sharing of certain technology abroad.

Impact

Access to both models was suspended on 12 June. Wikipedia says this was done to comply with a directive from the US Commerce Department. ^[1][3]

CNBC reported on 30 June that the administration had lifted the export controls on the models, and Anthropic redeployed them on 1 July. ^[1][2]