US Government Forces Anthropic to Pull Two AI Models Amid National Security Concerns

The US government forced Anthropic to pull its two newest AI models, Fable 5 and Mythos 5, late last week, citing national security concerns after Amazon researchers allegedly discovered a method to bypass Fable 5's guardrails. The ban, reported by TechCrunch on June 19, 2026, has sparked debate over whether the action is a genuine security measure or a politically motivated move against the company.

Anthropic suspended access to both models on June 18, 2026, affecting developers building on its platform and casting uncertainty over the company's planned IPO. Cybersecurity researchers have since signed an open letter calling the ban dangerous, noting that similar jailbreaks exist in other models.

SK Telecom Ties and the Mythos Model

The ban followed a dispute over Anthropic granting South Korean telecom giant SK Telecom access to its Claude Mythos model, according to people familiar with the matter cited by Wired. US officials expressed concerns about SK Telecom's alleged ties to China, which compounded when Amazon flagged vulnerabilities in Fable 5, a highly safeguarded version of Mythos, to the White House.

• Anthropic's Fable 5 and Mythos 5 were pulled on June 18, 2026, after a White House directive.
• Amazon researchers identified a jailbreak method that bypassed Fable 5's guardrails, prompting the government action.
• SK Telecom's access to Mythos raised national security concerns due to its alleged connections to China.
• Anthropic stated that the same jailbreak techniques exist in other models, questioning the ban's justification.
• The open letter from cybersecurity researchers argues the ban sets a dangerous precedent for AI regulation.

Regulatory Fallout and IPO Implications

The ban comes amid a broader regulatory push in Washington. Senator Bernie Sanders introduced legislation on June 19 that would impose a one-time 50 percent tax on the stock of large AI companies, including Anthropic, OpenAI, and xAI, paid in shares to create a public wealth fund. The bill, reported by The Next Web, goes further than any previous proposal and could complicate Anthropic's IPO plans.

Anthropic has not commented on the Sanders bill, but the company faces a dual challenge: navigating the government's security concerns while preparing for a public offering. The ban may inadvertently boost Anthropic's brand by framing it as a target of government overreach, as suggested by TechCrunch's Equity podcast. What comes next depends on whether Anthropic can negotiate a resolution with the White House or whether the ban escalates into a broader trade dispute with South Korea.