Anthropic has publicly accused Alibaba of orchestrating a large-scale distillation campaign aimed at extracting capabilities from its Claude AI models. The allegation, detailed in a letter sent to U.S. senators, adds fresh tension to the ongoing technology rivalry between the United States and China.
According to Anthropic, the e-commerce and technology giant used approximately 25,000 fraudulent accounts to generate over 28.8 million interactions with Claude between April 22 and June 5, 2026. The goal was to illicitly replicate the performance of Anthropic’s most advanced model, Claude Mythos Preview, using a technique known as knowledge distillation—a legitimate machine learning method that can be weaponized for model extraction attacks.
This technique allows bad actors to feed input-output pairs from a proprietary “teacher” model into their own “student” model, effectively creating a cheap replica of the original system. Anthropic claims that Alibaba and its AI lab Qwen were behind the campaign, marking what it describes as the largest known instance of such an attack on the company.
The accusation comes amid a rapidly closing frontier gap between Western and Chinese AI models. For example, Z.ai’s GLM-5.2 model, released shortly after Anthropic restricted global access to its most advanced model under U.S. government orders, has achieved benchmark performance nearly on par with leading Western frontier models. Z.ai has since captured a $128 billion market capitalization and plans to accelerate its pursuit of AGI.
This is not the first time Anthropic has raised alarm over distillation attacks. Earlier in February, the company alleged that several Chinese AI firms—including DeepSeek, Moonshot AI, and MiniMax—had collectively generated millions of interactions with its Claude platform. Anthropic warned that such attacks are becoming more sophisticated and require closer coordination between AI companies and governments.
The issue has also drawn attention in Washington. The Pentagon has added Alibaba to its list of Chinese military companies, a designation the company is contesting. Meanwhile, Reuters reported that the U.S. Commerce Department has so far held off adding DeepSeek to its trade blacklist, despite national security concerns, as officials weigh diplomatic repercussions.
Alibaba has not yet responded to requests for comment on the allegations.