Anthropic says Alibaba illicitly extracted Claude AI model capabilities

U.S. AI company Anthropic accused Alibaba, the Chinese technology and e-commerce giant, of illicitly extracting its Claude AI model capabilities in what it said was the largest known attack of its kind on the company, according to a letter seen by Reuters.

The strike by Alibaba is described as a “distillation” effort, which Anthropic has said involves training a less capable model on the outputs of a stronger one.

Anthropic said the campaign was conducted between ‌April 22 and ⁠June 5, ⁠2026, and generated more than 28.8 million exchanges with Claude through almost 25,000 fraudulent accounts.