Can U.S. Defense Secretary Mark Esper explain the intelligence that led to the killing of a top Iranian general? And what's the strategy if Iran retaliates in the future? In an interview with NPR, Esper answered those questions and more. Also, the Democratic presidential race is getting more personal. Tonight is the last Democratic debate before the Iowa caucuses. Apple is refusing to comply with the FBI's demand to unlock the phones of an alleged mass shooter. U.S. Attorney General William Barr isn't pleased. Is there a simple solution?