Operation Atlas, New York City's plan to protect itself from terrorist attacks, is likely to cost $700 million a year, much of it in overtime pay for police officers and firefighters. Mayor Michael R. Bloomberg has asked the federal government for money that would offset the costs of the program. While Congress has offered some $200 million in security spending, it has no intention of footing the entire bill. A close reading of the Constitution, however, suggests that it should. Article IV, Section 4 of the Constitution says, "The United States . . . shall protect each of [the states]...