Anthropic first released Mythos-class models in February 2026, but CEO Dario Amodei said it delayed broader access until June to build stronger cybersecurity safeguards.

Amodei laid out that reasoning Tuesday in a lengthy post on X, written in response to criticism from Nathan Calvin and defending the company’s approach to AI safety. He conceded the decision may have cost Anthropic a competitive edge. Releasing the models sooner, he argues, would have given organizations less time to prepare their infrastructure for increasingly capable AI-powered cyberattacks.

“We likely sacrificed a significant chunk of a several-month model lead,” Amodei writes.

Anthropic tells The New Stack that the delay follows a commitment in its Responsible Scaling Policy to require a strong argument that catastrophic risk is contained and to delay development and deployment as far as needed until it no longer believes it holds a significant lead.

Thank you for this, @_NathanCalvin. I appreciate and am a fan of the investigative work you’ve done on behalf of AI safety and believe your comments are coming from a constructive, honest place, and that it benefits the public to have people whose job is to scrutinize the actions… https://t.co/QZgPvh4tX4

In his criticism posted Monday, Calvin argues that Anthropic increasingly resembles a company racing to build superintelligence while weakening its commitments to preventing dangerous AI outcomes.

He points to the company’s more than $500 billion in computing deals, its growing use of AI to develop new models, and changes to its Responsible Scaling Policy , which establishes safeguards as models become more powerful.

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