Anthropic says new defenses cut Claude reasoning-token theft by up to 99%
Anthropic says it has deployed measures that reduced extraction of Claude's internal reasoning tokens (chain-of-thought steps) by about 90–99% against large-scale distillation attacks. The company says it now restricts access to reasoning steps, runs a classifier to detect extraction attempts and automatically bans flagged accounts (tens of thousands banned), and it named Chinese firms Zhipu and Moonshot as alleged participants whose efforts may have fed models like GLM-5.3; Anthropic warns stolen capabilities could be used in foreign military or surveillance systems and says legitimate users are sometimes affected.