Anthropic alleges Alibaba illicitly extracted Claude AI model capabilities in the largest alleged model-distillation attack on the company.
US AI company Anthropic has accused Alibaba, the Chinese technology and e-commerce giant, of illicitly extracting its Claude AI model capabilities in what it describes as the largest known attack of its kind on the company, according to a letter seen by Reuters.
Anthropic characterized the strike as a "distillation" effort—a technique involving the training of a less capable model on the outputs of a stronger one. The company said the campaign was conducted between April 22 and June 5, 2026, generating more than 28.8 million exchanges with Claude through approximately 25,000 fraudulent accounts. According to Anthropic, distillation represents a method to help accelerate China's ability to reach Anthropic's advanced Mythos Preview capabilities.
The campaign was conducted by operators affiliated with Alibaba and Alibaba Qwen, Alibaba's AI lab. Alibaba did not immediately respond to a request for comment.
Anthropic sent the letter, dated June 10, to US senators Tim Scott and Elizabeth Warren—the chair and ranking member, respectively, of the US Senate Banking Committee—ahead of a scheduled hearing on artificial intelligence. The company stated it was supportive of US government efforts to combat such attacks, including partnering with private sector AI companies through threat-intelligence sharing and other collaborative exercises.
This represents the latest in a pattern of similar campaigns. In February, Anthropic identified attacks by Chinese AI startup DeepSeek—whose low-cost model sent shockwaves through the technology world in January 2025—and two other Chinese AI labs. DeepSeek's operation involved over 150,000 exchanges, while Moonshot AI conducted attacks at a scale exceeding 3.4 million exchanges and MiniMax over 13 million. Anthropic noted at the time that these campaigns were growing in "intensity and sophistication" and that addressing the threat would require "rapid, coordinated action among industry players, policymakers and the global AI community."
In June, Alibaba was added to the Pentagon's list of Chinese military companies, a designation it is challenging. However, the Commerce Department has held off placing DeepSeek on a trade blacklist, despite it being deemed a national security risk by an interagency governmental committee, as Reuters exclusively reported, amid efforts to avoid escalating tensions with Beijing.
On June 12, two days after Anthropic sent its letter, the Commerce Department imposed restrictions on Anthropic's latest Mythos and Fable AI models, citing concerns that they could be deployed by military and intelligence users in China and other countries of concern. The restrictions resulted in Anthropic disabling access to the models globally.