NYC Is Getting a New High-Tech Defense Perimeter. Let's Hope It Works

At the southernmost end of Brooklyn, just off Dead Horse Bay, there's a weather-beaten helipad where the New York Police Department keeps a gray unmarked twin-engine Bell 412 helicopter. Detective Brendan Galligan ushers me aboard. "We don't really let people see this," he says. We climb in behind the pilot and find ourselves facing a console with three screens: One shows a map of the city; another, an interface for checking license plates and addresses; and the third, the view from a gyro-stabilized L-3 Wescam camera attached to the...