Last week, FBI agents arrested a 19-year-old man, accused of trying to detonate what he thought were explosives at a Christmas tree-lighting ceremony in Portland. But the bomb was a fake, given to the suspect by undercover federal agents. NPR's Robert Siegel speaks to the mayor of Portland, Sam Adams, who didn't know about the sting operation because five years ago, Portland became the first U.S. city to opt out of the Joint Terrorism Task Force.