(Editor's Note: This story has been updated to reflect that the Missile Defense Agency and Lockheed Martin are examining the possibility of a five-year deal for the Terminal High Altitude Area Defense System, and not negotiating a contract as originally reported. The agency and contractor have not advanced beyond the exploratory stage of whether it makes fiscal sense to secure a multiyear agreement.) The Missile Defense Agency is examining the possibility of a five-year contract to purchase approximately 150...