LOS ANGELES (Reuters) - A U.S. veteran of the war in Afghanistan who prosecutors say plotted to detonate a nail bomb at a Los Angeles-area white nationalist rally, hoping to cause mass casualties, was arrested in an FBI online sting operation, federal prosecutors said on Monday. Mark Steven Domingo, 26, a U.S. Army infantryman who fought in Afghanistan and recently converted to Islam, was taken into custody on Friday after being given what he thought was a live bomb to use in the attack by an FBI informant, law enforcement officials said. “Often we are asked what keeps us up...