The United States believes that whoever controls fifth-generation cellular networks, known as 5G, will have a global advantage for decades to come. The fear is that China is almost there. 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.