Days before the Trump administration forced Anthropic to take its most powerful AI models offline globally, the White House ordered the company to revoke a single customer’s access: SK Telecom, South Korea’s largest telecommunications provider. The reason, according to administration officials, was the company’s alleged ties to China.
The SK Telecom story is the missing piece of the Claude Fable 5 and Mythos 5 shutdown that has dominated AI news for the past week. It reveals how a $100 million investment by a Korean telecom in 2023, combined with a legacy joint venture with China Unicom, spiraled into a national security crisis that ultimately deprived the entire world of access to Anthropic’s most capable models.
SK Telecom invested $100 million in Anthropic in August 2023, securing roughly 2% of the company (later diluted to approximately 0.3%). The relationship deepened over time: SK Telecom became a commercial partner, co-developing a telco-specific large language model by fine-tuning Claude for customer service and marketing.
On June 4, 2026, SK Telecom joined Project Glasswing, Anthropic’s restricted early-access program for its most powerful model, Claude Mythos. The consortium of roughly 150 organizations across 15 countries included US government agencies, Big Tech companies, and allied foreign partners. SK Telecom gained access to Mythos, a model capable of autonomously discovering zero-day vulnerabilities and generating exploits.
Five days later, on June 9, Anthropic publicly launched Claude Fable 5, a safeguarded variant of Mythos, to widespread acclaim as the most capable public AI system ever released.
The White House Intervenes
According to reporting by Wired’s Louise Matsakis and Maxwell Zeff, the White House first asked Anthropic to revoke only SK Telecom’s access to Mythos. US officials raised concerns about SK Telecom’s legacy investment in UNISK, a joint venture with China Unicom valued at roughly $17 million, as well as broader business interests of SK Group, the parent conglomerate, across Chinese semiconductors and energy.
SK Telecom denied the allegations. An SK Telecom representative told a Korean newspaper that “the anonymous insider’s remarks in foreign media lack verified facts, and our company has no ties to China.” The companys China operations in 2024 generated just $1.9 million in revenue with seven employees.
Notably, the formal export control letter from Commerce Secretary Howard Lutnick to Anthropic CEO Dario Amodei did not mention SK Telecom or China at all, according to a person close to Anthropic.
Anthropic immediately complied with the request to revoke SK Telecom’s access. But the broader situation escalated rapidly.
The Escalation
The trigger for the global shutdown was not SK Telecom. It was Amazon researchers who reported to the administration that Fable 5’s safety guardrails could be circumvented, potentially unlocking Mythos-level capabilities related to cybersecurity.
The confluence of two concerns, SK Telecom’s alleged China exposure and the Fable 5 jailbreak, led the administration to conclude it could not trust Anthropic to safeguard its technology selectively. On June 12 at 5:21 PM ET, Lutnick sent an export control directive ordering Anthropic to suspend access for any foreign national, including foreign-national Anthropic employees. The company, unable to verify the nationality of every API caller in real time, disabled both Fable 5 and Mythos 5 for all customers worldwide.
All 150 Project Glasswing participants across 15 countries lost access, not just SK Telecom.
The Broader Pattern
The SK Telecom saga reveals the standards by which the US government is now judging AI partnerships. A $17 million legacy joint venture with a Chinese state-owned enterprise was sufficient to trigger concerns about access to frontier AI capabilities. The timeline shows that the administration was willing to act on those concerns through targeted revocation before the wider export control directive was issued.
The incident has alarmed allied governments, particularly in South Korea. Calls for “AI sovereignty,” meaning indigenous LLM development to reduce dependence on US frontier models, have intensified. LG Uplus, another Korean telecom, stated it never received access to Mythos at all.
As of June 18, Anthropic engineers remain in Washington for in-person talks with the Commerce Department. No restoration deal has been announced. The models that 150 organizations across 15 countries were using for cybersecurity research and development remain offline, in large part because of a relationship with a Korean telecom that began with a $100 million check in 2023.
Sources: Wired (June 17, 2026); EuropeSays (June 17, 2026, republishing Wired); BusinessKorea (June 2026); Anthropic official statement (June 12, 2026)