According to Bloomberg, Anthropic sent a confidential letter to US senators and White House officials accusing Alibaba's Qwen lab of using nearly 25,000 fraudulent accounts to make massive unauthorized access to Claude. The letter claims that between April and June 2026, those accounts made 28.8 million interactions with Claude, specifically targeting its software engineering and agentic reasoning capabilities. Anthropic warns that Alibaba and other Chinese labs are systematically and illegally using the outputs of US frontier models to train their own at extremely low R&D cost.