Amazon Web Services announced that Anthropic’s Claude Fable 5 models are available again to customers on Bedrock, featuring even stronger guardrails to prevent misuse. The article states that the most recent generation of frontier models, such as Anthropic’s Claude Mythos, have powerful new capabilities, particularly in cybersecurity, which AWS experienced firsthand as part of Project Glasswing. AWS has been working closely with Anthropic and other industry partners in Project Glasswing to refine guardrails for this new class of models, agreeing that preventing adversaries from gaining access to the ability to do deep vulnerability research is the most important objective. The article emphasizes that new guardrails must continue to be developed as more is learned about current ones and as new models are released, and that any issues with models after release must be addressed appropriately. Anthropic has published a blog, Redeploying Fable 5, explaining their thinking about the capabilities of this new class of models.