Although no specific plot has been identified, revelers this Fourth of July can expect extraordinary security -- from expanded patrols and SWAT units to biological weapon response teams and undercover officers mingling with celebratory crowds. "It's absolutely not a joke," said New York police Sgt. Thomas Horvath, who took ABC News on patrol around New York City's waterways. "The threat is very real. On the day of the [July 4] event, we're going to put out basically every asset we have."...
