Anthropic Accuses Alibaba of Largest-Ever Distillation Attack on Claude

What happened

Anthropic sent a letter dated June 10 to the US Senate Banking Committee (made public June 24) accusing Alibaba of "brazenly" and "illicitly" extracting Claude's capabilities. Between April 22 and June 5, 2026, approximately 25,000 fraudulent accounts conducted 28.8 million exchanges.

Context and impact

Anthropic called this "the largest known distillation attack on Anthropic to date." The letter was addressed to Senators Tim Scott (R) and Elizabeth Warren (D); Senators Hagerty and Kim plan legislation to sanction Chinese firms misusing US AI outputs. It lands amid escalating tensions over export controls on the Fable 5 and Mythos 5 models.

Details

• 28.8 million API exchanges over 6 weeks
• ~25,000 fraudulent accounts
• Anthropic claims Alibaba ignored Trump administration warnings
• Goal allegedly was to improve the competing Qwen model
• Senators preparing sanctions legislation