NEW YORK CITY, N.Y. -- The Airtrain at JFK Airport is a fully automated system: It has no train operator, no passenger screening and an almost nonexistent police presence. And that, says the Port Authority police union, makes it one of four major vulnerabilities the Port Authority is overlooking threats so sensitive, union officials won't name the other three. "There's no scanning of bags, there's no scanning passengers. We should have uniformed personnel on that transportation corridor. We don't, in any way," said Senator Greg Ball. Friday, Ball's homeland security committee heard testimony from union officials and others who detailed...