Anthropic’s decision to shut down Claude Mythos and Fable 5 followed two separate problems that escalated quickly, according to a report cited by THE DECODER. One centered on SK Telecom’s access to Mythos. The other involved security flaws in Fable 5 that could be used to bypass safety restrictions.
Taken together, those incidents led the White House to lose confidence in Anthropic and push both models completely offline.
How SK Telecom became part of the Anthropic crisis
The first issue began with access. South Korean telecom giant SK Telecom had access to Claude Mythos through Anthropic’s partner program, Project Glasswing.
WIRED reports that US officials grew alarmed over what they viewed as SK Telecom’s alleged ties to China. The White House then told Anthropic to cut off SK Telecom’s access. Anthropic complied right away.
That sequence matters because the concern was not simply about a customer using an AI model. The access came through a partner program, which made the relationship more direct and more sensitive once US officials raised concerns.
SK Telecom denied any China connections to a Korean newspaper. At the same time, the company is part of the broader SK Group, which has major business interests in China. SK Group also held a stake in the state-owned Chinese carrier China Unicom until 2009.
The source does not say that SK Telecom misused Mythos. It also does not say that China Unicom had any role in the incident. The reported concern was about alleged ties, the broader corporate context, and the level of access SK Telecom had through Project Glasswing.
Why Project Glasswing access drew attention
Project Glasswing is described in the source as Anthropic’s partner program. Through that program, SK Telecom had access to Mythos, one of the AI models later shut down.
Partner access can become a focal point when outside officials question who can use a model and under what conditions. In this case, the White House’s response was direct: Anthropic was told to cut off SK Telecom’s access, and the company did so immediately.
The important point is the chain of events. SK Telecom had access to Mythos. US officials became alarmed over alleged China ties. The White House intervened. Anthropic removed that access.
That action did not end the wider crisis. It was followed soon after by a second problem involving another model, Fable 5.
Security flaws in Fable 5 made the situation worse
Shortly after the SK Telecom issue, Amazon and other companies flagged security flaws in Fable 5. According to the source, those flaws could be used to bypass safety restrictions.
This shifted the problem from a dispute over access to a broader question about whether Anthropic’s models could be trusted to remain within their intended limits. The source does not provide technical details about the flaws. It also does not identify the other companies beyond Amazon.
Still, the reported concern was serious enough to compound the earlier alarm. One incident involved Mythos and SK Telecom’s access. The next involved Fable 5 and safety restrictions. Together, they led to a larger loss of confidence.
That distinction is important. The shutdown was not presented as the result of one isolated problem. It followed a sequence in which concerns about access were soon followed by concerns about model security.
Why both Claude models were forced offline
The final outcome was severe: both Claude Mythos and Fable 5 were forced completely offline. According to the source, the White House lost confidence in Anthropic because of the two incidents together.
The first incident prompted Anthropic to cut off SK Telecom’s access to Mythos. The second involved security flaws in Fable 5 that Amazon and other companies flagged. The combined effect pushed the situation beyond a narrow access decision.
For Anthropic, the episode shows how quickly trust can deteriorate when model access and model safety concerns appear close together. For partners, it shows that access through a program like Project Glasswing can become subject to outside scrutiny when officials raise concerns.
The source does not say whether Claude Mythos or Fable 5 will return. It also does not describe what changes Anthropic may make after the shutdown. What it does make clear is the reported order of events: SK Telecom’s Mythos access drew concern, Anthropic cut off that access, Fable 5 flaws were then flagged, and the White House forced both models offline.
What is known and what remains limited
The known facts are narrow but consequential. SK Telecom had access to Mythos through Project Glasswing. US officials were alarmed by alleged China ties. SK Telecom denied any China connections to a Korean newspaper. SK Telecom’s parent group context included major business interests in China and a former stake in China Unicom until 2009.
The second known fact is that Amazon and other companies flagged security flaws in Fable 5. Those flaws could be used to bypass safety restrictions. After both issues, the White House lost confidence in Anthropic and forced Claude Mythos and Fable 5 completely offline.
What remains unclear from the source is equally important. The article does not present evidence that SK Telecom misused Anthropic’s models. It does not provide technical details about the Fable 5 flaws. It does not say what specific steps Anthropic may take next.
That leaves the central picture: a partner access concern and a model safety concern arrived close together, and the combined pressure was enough to take two Anthropic models offline.