The Israeli spyware firm NSO Group has made a habit of brushing off bad news stories about authoritarian regimes’ use of its product to snoop on dissidents by simply denying its involvement. The company cannot, however, write off the latest headline: The United States has added NSO to a blacklist prohibiting it from receiving U.S. technologies after finding its tools have indeed helped foreign governments “maliciously target” officials, activists, academics and journalists. The move on Wednesday was a step major and modest at the same time. The practical, legal implications are relatively straightforward: NSO Group and the other three entities...