The Biden Administration will soon have to decide whether to impose sanctions on India under the Countering America’s Adversaries Through Sanctions Act (CAATSA) for India’s purchase of the Russian S-400 defense system. CAATSA, passed in the wake of Russian interference in the U.S. 2016 presidential election, was designed to punish Russia by discouraging trade with its defense and intelligence sectors. In India’s case, however, sanctions are unlikely to alter its longstanding defense relationship with Russia. They could, however, undermine the U.S.–Indian strategic partnership, handing Moscow a victory in the process. The Biden Administration has a clear path for issuing India a CAATSA waiver, and should exercise it.