Anthropic publicly accuses Alibaba of largest known illicit Claude distillation campaign (28.8M+ queries)

Anthropic accused Alibaba of conducting a large-scale distillation campaign to illicitly extract capabilities from its Claude AI model, according to a letter seen by Reuters. The U.S. AI company said the campaign ran from April 22 to June 5, 2026, and produced more than 28.8 million exchanges with Claude through almost 25,000 fraudulent accounts. It called the operation the largest known attack of its kind against the company and said it was carried out by operators affiliated with Alibaba and Alibaba Qwen, the company's AI lab. Anthropic sent the letter, dated June 10, to Sens. Tim Scott and Elizabeth Warren ahead of a U.S. Senate Banking Committee hearing on AI. Alibaba did not immediately respond to a request for comment. The letter described distillation as a technique to help accelerate China's ability to reach Anthropic's advanced capabilities.