A New York Times investigation found that the United States is actively infiltrating Russia’s electric power grid. We look at what that means for the future of cyberwarfare. Guest: David E. Sanger, a national security correspondent for The New York Times and the author of “The Perfect Weapon: War, Sabotage, and Fear in the Cyber Age.” For more information on today’s episode, visit nytimes.com/thedaily. Background reading: The cyberattacks on Russia’s power grid are intended partly as a warning, and partly to be poised to act if a major conflict broke out between Washington and Moscow.In response to The Times’s report, the Kremlin warned that American attacks could escalate into cyberwar.