For many Americans, Russian hacking remains a story about the 2016 election. But there is another story taking shape. Marrying a hundred years of expertise in influence operations to the new world of social media, Russia may finally have gained the ability it long sought but never fully achieved in the Cold War: to alter the course of events in the U.S. by manipulating public opinion. The vast openness and anonymity of social media has cleared a dangerous new route for antidemocratic forces.