The Obama administration on Sunday acknowledged that U.S. intelligence agencies missed some red flags that could have helped unravel the plot to bomb a U.S. airliner on Christmas Day, but said there had been no single "smoking gun" indicating that the attack was coming. John Brennan, the White House's top counterterrorism official, used a round of appearances on the Sunday morning talk shows to defend the administration's handling of the attempted attack. A 23-year-old Nigerian, Umar Farouk Abdulmutallab, had allegedly tried to set off explosives that he had smuggled underneath his clothing onto a Northwest Airlines flight from Amsterdam to...