Anthropic said Friday it has cut access to two powerful artificial intelligence (AI) models after a United States government order citing national security concerns.

The sudden block marks a major escalation in Anthropic’s growing showdown with the Trump administration after failed negotiations earlier this year over potential US military and intelligence use of its technology.

The order is potentially a major setback for Anthropic's plans to take the company public later this year.Do large-scale AIs make society's problems worse?To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video

What did Anthropic say about the block?

The San Francisco-headquartered firm said in a statement that it received a directive to block its Claude Fable 5 and Claude Mythos 5 for all foreign nationals.Fable 5 and Mythos 5 are the newest versions of the Claude AI model, released on June 9. The first is widely available to the public, while the latter is mostly restricted to vetted organizations.