Amazon.com Inc. (AMZN) CEO Andy Jassy was reportedly behind the security concerns that led to a U.S. export control ban on Anthropic's two "Mythos-class" AI models, built for highly complex reasoning and long-horizon agentic work.

The Wall Street Journal reported Saturday, citing sources, that Jassy told Treasury Secretary Scott Bessent that Amazon researchers used the Fable 5 model to obtain information usable in cyberattacks, prompting Anthropic's global shutdown of the models.

On Friday, Anthropic disabled access to Fable 5 and Mythos 5 after the government directed the company to bar foreign nationals from the systems on national security grounds.

The Information and Reuters similarly reported the concerns, attributing them to Amazon, a major Anthropic investor.

Amazon did not immediately respond to MarketDash's request for comment.

In April, Anthropic committed to spending over $100 billion on Amazon Web Services infrastructure, including Trainium chip capacity, while Amazon added $5 billion in fresh investment in the startup, building on its earlier $8 billion stake.

David Sacks, former White House AI and Crypto Czar who currently co-chairs the President's Council of Advisors on Science and Technology, said on X that a "highly credible trusted partner" of both Anthropic and the U.S. government, testing Fable, found a jailbreak. Sacks wrote, "The Admin asked Dario to fix the jailbreak or de-deploy the model. Dario refused."

Earlier, in a blog post, Anthropic said the capabilities apparently causing government concern are already available in other publicly accessible AI models.

Amazon became a major shareholder in the Dario Amodei-led AI startup Anthropic in September 2023. The company has been in the news recently for various reasons. The Pentagon designated Anthropic's Claude models a supply chain risk earlier this year. The company is also expected to go public later this year.