Anthropic tells Senate Alibaba ran 28.8M-query distillation attack on Claude

A June 10 letter names Alibaba's Qwen lab in the largest distillation campaign Anthropic has ever filed against — and it dwarfs all three Chinese labs named in February combined.

Anthropic told the U.S. Senate Banking Committee that Alibaba’s Qwen AI lab ran 28.8 million query exchanges against Claude through nearly 25,000 fraudulent accounts between April 22 and June 5, framing it as the largest known distillation campaign the company has ever filed against a single actor. The June 10 letter, addressed to Chair Tim Scott and Ranking Member Elizabeth Warren, was first reported by Bloomberg and subsequently confirmed by CNBC, Reuters and Nikkei Asia.

The scale is the point. Anthropic’s February disclosure naming DeepSeek (over 150,000 exchanges), Moonshot AI (over 3.4 million) and MiniMax (over 13 million) totaled roughly 16 million queries across about 24,000 fake accounts. Alibaba alone, in six weeks, ran nearly double that.

Sarah Heck, Anthropic’s head of policy, wrote that the campaign was “carried out illicitly, systematically, and at industrial scale to harvest U.S. AI capabilities across frontier labs and repackage them as their own without incurring the training and R&D costs required to train U.S. frontier models.” Alibaba didn’t respond to Reuters’ request for comment.

Read in sequence, the policy machinery has been moving faster than the disclosures. An April 24 OSTP memorandum committed the White House to sharing distillation intelligence with U.S. labs. On June 8, the Pentagon added Alibaba to its Chinese military companies list. Commerce Secretary Howard Lutnick has since signed an order blocking foreign nationals from Anthropic’s Fable 5 and Mythos 5 models, the successors to Mythos Preview. Senators Bill Hagerty and Andy Kim are drafting a defense-legislation amendment to sanction entities running industrial-scale distillation.

What makes the Qwen filing analytically distinct from February isn’t only the volume. It’s the timing: the campaign began two days before the OSTP memo and ended three days before Alibaba landed on the Pentagon list. The export-controls apparatus from the late-2010s Huawei era is being retooled for a target it wasn’t designed for, an API endpoint, and the Senate letter is the document forcing the issue onto a committee that usually handles capital markets, not model weights.