SK Telecom named as the Korean carrier at the center of Anthropic's Mythos export controls controversy - access was revoked days before White House took Mythos and Fable 5 offline for all foreign nationals

SK Telecom identified as carrier at center of Anthropic Mythos export controls controversy

Wired has identified SK Telecom as the South Korean telecom company whose access to Anthropic's Claude Mythos model the White House ordered revoked over alleged ties to China.

SK Telecom, South Korea's largest wireless carrier, was among roughly 150 organizations added to Anthropic's Project Glasswing in early June, the program through which Anthropic distributes Mythos for vulnerability detection. The White House asked Anthropic to revoke the carrier's access shortly after that expansion, and the company complied immediately. No export controls were threatened at that point, according to Wired.

SK Telecom's China ties and parent group interests

SK Telecom's footprint in China is minimal, generating roughly $1.9 million in Chinese revenue in 2024 and employing seven people in the country, according to its annual report. The national-security concern attaches instead to its parent, SK Group, whose affiliates hold extensive interests in Chinese semiconductors, energy, and other sectors.

Despite that relatively small footprint, the carrier has a deeper history within the country, having formed a wireless joint venture called UNISK with state-owned China Unicom in 2004. It then invested $1 billion in China Unicom convertible bonds in 2006 that converted into a roughly 6.6% stake, which was sold in 2009 for $1.3 billion. SK Telecom has kept a residual interest since then, listing a UNISK investment worth roughly $17 million in its 2025 filing with the U.S. Securities and Exchange Commission.

Industry access and the Fable 5 guardrail bypass

SK hynix belongs to the same SK Group, and it received Mythos access in the same expansion, as did Samsung. The two rank among the largest suppliers of the memory and logic silicon that underpins AI hardware, and both joined Anthropic's funding round as strategic investors.

The export controls followed a separate dispute, however, when Amazon, Anthropic's largest investor with a cumulative stake of about $13 billion, flagged a guardrail bypass in Fable 5 to the White House after researchers prompted the model to read a codebase and fix its flaws, turning it into a vulnerability-discovery tool. Amazon CEO Andy Jassy reportedly raised the findings with administration officials directly, which then led to the Commerce Department's order on June 12 barring all foreign nationals - including immigrants inside the U.S. - from accessing Fable 5 and the underlying Mythos 5.

Rather than filter users by nationality, Anthropic disabled both models for everyone. The company said the demonstration it reviewed surfaced only a small number of previously known, minor vulnerabilities, and that banning a capability common to other frontier models would halt deployments across the industry.

Industry response and ongoing negotiations

About 100 cybersecurity professionals, including former Facebook security chief Alex Stamos and Luta Security's Katie Moussouris, signed an open letter arguing that while Mythos-class models are "quite good" at finding and weaponizing software flaws, they "are not uniquely good," calling for the controls to be lifted.

Mythos 5 and Fable 5 remain offline as Anthropic and the White House continue negotiations over restoring access. Anthropic opened a Seoul office on June 17 and signed a memorandum of understanding with South Korea's Ministry of Science and ICT (Information and Communication Technology), naming SK Telecom among its local partners.

SK Telecom has denied the allegations, telling a Korean newspaper that the anonymous claims in foreign media "lack verified facts," and that it has no ties to China.