Anthropic, SK Telecom and the White House Mythos dispute

Anthropic disabled access to its Claude Mythos model and the safeguarded Fable 5 after the White House demanded that access be restricted to US nationals, following SK Telecom’s inclusion among early Mythos recipients and Amazon researchers flagging vulnerabilities in Fable 5. The White House later ordered Anthropic to revoke access to Mythos and Fable 5 for all foreign nationals, including immigrants inside the US.

What happened?

Anthropic cut access after the White House decided it could not trust the company to safeguard its most advanced AI, citing SK Telecom’s access and Amazon-identified vulnerabilities. The White House’s action followed a spat over Anthropic granting South Korean telecom giant SK Telecom access to Claude Mythos and Amazon researchers flagging that some Fable 5 guardrails could be circumvented. Anthropic had initially limited early Mythos access to a small group via Project Glasswing, and expanded that program to roughly 150 companies before this dispute.

Anthropic released Fable 5, a highly safeguarded version of Mythos, to the public on June 9. Amazon later flagged vulnerabilities it identified in Fable 5 to the White House, saying it was possible to circumvent some guardrails and access Mythos’ cybercapabilities, a claim Anthropic and outside cybersecurity experts have disputed, saying those risks are not unique to Claude.

How is SK Telecom connected to Mythos and why did it alarm US officials?

SK Telecom was one of the organisations added to Project Glasswing as Anthropic expanded the program after weeks of collaboration with outside experts and the US government. SK Telecom has invested in Anthropic several times, including a $100 million investment in 2023 that coincided with a commercial partnership to build an AI model for telecommunications.

US officials were concerned about what they alleged were SK Telecom’s ties to China, a worry that intensified when Amazon raised the Fable 5 issues. SK Telecom told a Korean newspaper the "anonymous insider's remarks in foreign media lack verified facts, and our company has no ties to China." The company generated about $1.9 million in revenue from China in 2024 and employed seven people there, according to its annual report. SK Telecom is part of SK Group, whose affiliates maintain broader business interests in China.

The record shows deeper historical links to China: SK Telecom and China Unicom formed a joint venture called UNISK in 2004; in 2006 SK Telecom invested $1 billion in convertible bonds issued by China Unicom’s Hong Kong–listed unit that became a roughly 6.6 percent equity stake; SK Telecom sold that stake back in 2009 for approximately $1.3 billion. In its 2025 SEC filing SK Telecom listed an investment in UNISK valued at roughly $17 million.

Why it matters

The White House demanded a hard line: revoke foreign access to Anthropic’s most capable models. That puts commercial partnerships and multinational early-access programs at risk, especially for firms with historical ties or investments in China. Companies that had been part of Project Glasswing, about 150 organisations, now face sudden uncertainty over continued access to advanced models and any products built on that access.

The dispute also exposes a governance tension: the US asked Anthropic to limit access by nationality, a restriction the company said would be difficult to implement while preserving privacy, and instead Anthropic disabled access entirely. Negotiations between the White House and Anthropic over restoring Claude Mythos and Fable 5 continued for days after the order.

What to watch

Watch whether the White House moves from an order to targeted export controls with explicit rules for foreign access, and whether Anthropic restores Model access only to US entities or presses back. Also watch for any public technical disclosures or third-party audits addressing the vulnerabilities Amazon flagged in Fable 5; Amazon’s report to the White House triggered part of the intervention.

If regulators or the White House publish a formal rule or list of sanctioned recipients, that will be the clearest signal of how access to advanced models will be governed going forward.