ORLANDO, Fla. — Embracing grieving Orlando families and appealing anew for national action, President Barack Obama claimed a threat to all Americans' security Thursday as a strong reason to tighten U.S. gun laws. Counterterror campaigns overseas, he declared, can never prevent all "lone wolf" attacks like the one that killed 49 people in Orlando. Speaking at a makeshift memorial to the victims, Obama said the massacre at a gay nightclub was evidence that "different steps" are needed to limit the damage a "deranged" person set on committing violence can do.