Anthropic blocked public access to Fable 5 and Mythos 5 on Friday after the Trump administration imposed export restrictions on the recently released artificial intelligence models due to security concerns.

The White House imposed such restrictions “partly over suspicions that a China-linked group had accessed” the Mythos 5 model, a person familiar with the matter told Semafor Saturday. If confirmed, the report would mark a significant development over the broader debate about national security risks associated with Chinese access to American AI models.