President Trump was so confident thahe would reach a nuclear pact with North Korea that he scheduled a signing ceremony before an agreement had even been struck. Here’s how it all unraveled. 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.