The Sudden Disappearance of Fable 5
Three days after Anthropic launched Fable 5, calling it the most powerful model in the company’s history, the model was abruptly taken offline. Not just in one country or for a specific group of users, but completely removed from public access around the world. This unexpected move was reportedly triggered by a phone call from one of Anthropic’s own investors.
According to the Wall Street Journal, Amazon CEO Andy Jassy informed Treasury Secretary Scott Bessent and other officials that Amazon researchers had used Fable 5 to extract information that could be exploited in cyberattacks. In response, the Commerce Department sent a letter to Anthropic CEO Dario Amodei on June 12, invoking national security concerns to restrict foreign nationals, including Anthropic’s own foreign-born employees, from accessing Fable 5 and Mythos 5.
Why Amazon’s Warning Carries Unusual Weight
What makes this situation unusual is the source of the warning. Amazon has invested approximately $13 billion in Anthropic and secured a $100 billion AWS infrastructure spending commitment from the company in return. Anthropic was expected to pursue an IPO later in 2026.
An Amazon spokesperson confirmed the general outline of the story without providing details. “It’s not uncommon for governments to seek our counsel on potential security risks,” the spokesperson said, declining to share specifics of the discussions, according to TechCrunch. The spokesperson also confirmed that AWS itself was affected by the model cutoff since Anthropic’s models run on Amazon’s cloud infrastructure.
What Amazon’s Researchers Reportedly Found
According to The Next Web, Amazon researchers used a series of prompts to get Fable 5 to provide information that was supposed to be off-limits, specifically related to cyberattack techniques. Katie Moussouris, CEO of security firm Luta Security, reviewed the underlying report shared by Anthropic and described the technique to the Washington Examiner as a way of bypassing Fable’s guardrails to access the underlying Mythos model’s broader capabilities.
David Sacks, the former White House AI czar who now co-chairs the President’s Council of Advisors on Science and Technology, offered his own account in a post on X. He wrote that “a highly credible trusted partner of both Anthropic and the USG who was testing Fable came forward with a jailbreak of those guardrails,” and that the administration asked Anthropic CEO Dario Amodei to fix the issue or remove the model. “Dario refused,” Sacks added.
Anthropic’s Response and Its Scale
Anthropic confirmed it was complying with the government’s directive while disputing the framing of the situation. “We are complying with the government’s legal directive and are removing access to Fable 5 and Mythos 5 for all users,” the company said, according to the Washington Examiner.
“We disagree that the finding of a narrow potential jailbreak should be cause for recalling a commercial model deployed to hundreds of millions of people.”
The shutdown impacted enterprise customers, including banks and government agencies that had been using Mythos-class models for vulnerability discovery and complex reasoning tasks. Anthropic concluded that attempting to selectively block foreign nationals in real time was not technically feasible, so it disabled both models globally instead.
What This Episode Reveals About the Broader AI Landscape
Fable 5 and Mythos 5 trace back to Claude Mythos Preview, a model that Anthropic initially restricted to launch partners including Amazon, Google, Apple, Nvidia, and CrowdStrike under Project Glasswing. This program was designed to let those companies find and fix security flaws before any wider release, a structure that Anthropic hoped would prevent exactly this kind of incident.
This is not the first time Anthropic has clashed with the federal government. The company is currently suing the administration in a separate case after the Pentagon blacklisted it for refusing to remove restrictions on military use of Claude, according to Reuters.
The timing adds pressure to Anthropic. Fable 5 launched on June 9 as the company’s flagship model, was pulled globally on June 12, and the company is simultaneously navigating IPO preparations that this kind of global shutdown does not make easier.
The Precedent Question
Industry watchers are now focused on the precedent set by this episode. If a major cloud provider can trigger an export control action against its own portfolio company by raising concerns directly with the Treasury Secretary, that gives large cloud and infrastructure partners a new form of leverage over the AI labs that depend on them.
What It Means for the Amazon and Anthropic Relationship
The practical relationship between the two companies is unlikely to change immediately. AWS remains central to Anthropic’s infrastructure, and Amazon’s $13 billion investment and $100 billion compute commitment are not going anywhere over a single incident. But the episode adds a new dimension to how that relationship is understood from the outside.
Amazon is simultaneously Anthropic’s largest financial backer, its primary infrastructure provider, and, in this case, the source of the security concern that led to a government-ordered shutdown of Anthropic’s flagship product. For an industry that has spent the past two years arguing that AI companies and their major partners are aligned on safety, this is the clearest public example yet of what happens when that alignment breaks down in practice, even temporarily, and even between two companies that need each other to succeed.