Fable 5’s Ban Has a New Name Behind It: SK Telecom

Fable 5 wasn't pulled over a jailbreak alone — the explanation everyone first reached for. A week into Anthropic's U.S. export ban, WIRED has named the company at the real center of it: SK Telecom — South Korea's largest mobile carrier and a $100 million Anthropic investor since 2023 — whose access to the unreleased Claude Mythos model the White House ordered revoked over suspected ties to China, days before the blanket directive came down.

The thread runs through Project Glasswing, Anthropic's cybersecurity consortium that hands a preview of the 10-trillion-parameter Mythos model to vetted partners to hunt zero-days. SK Telecom had gained early Mythos access through that program on top of its 2023 investment and a partnership to build telecom-focused AI. According to the reporting, Washington flagged the carrier as a national-security concern and asked Anthropic to cut its access — which the company did immediately, before the wider ban.

That wider ban landed on June 12, when the Trump administration — through Commerce Secretary Howard Lutnick, invoking the Export Controls Reform Act of 2018 — forced Mythos and the public Fable 5 model offline for all foreign nationals. Reports this week add that the pressure had been building behind the scenes: PCAST co-chair David Sacks is said to have offered Anthropic a pre-ban choice — fix the jailbreak or voluntarily pull the model — and that CEO Dario Amodei refused both, hardening the standoff into a full directive.

SK Telecom flatly denies the premise. The carrier told a Korean newspaper that the anonymous claims in foreign media "lack verified facts," and that it has no ties to China. The denial matters: the entire export action rests on the assertion that a frontier model's most sensitive capabilities reached an entity Washington considers a proxy risk — a claim that, if it does not hold up, reframes the ban from a security necessity to an overreach. It is also a reminder that the same Glasswing program built to defend critical infrastructure is now the channel regulators worry could leak capability abroad.

Where it leaves Anthropic is awkward but improving. At the company's Seoul office launch on June 18 — alongside deployments at NAVER, Samsung SDS and LG CNS — international managing director Chris Ciauri said he was "very confident" both Mythos and Fable 5 would return "in the coming days," the most concrete timeline since the shutdown. Negotiations with the administration have continued since June 12, even as security researchers argue the government's core condition — eliminating every jailbreak — is technically impossible for any frontier model.