The Defense Department has added a small buffer to its limited inventory of intercontinental ballistic missile-killing interceptors, growing the Ground-based Midcourse Defense program by two guided missiles after harvesting enough spare parts to assemble a pair of the most modern variants of the homeland defense interceptor. In a new twist, the Missile Defense Agency will not specify the number of interceptors in the GMD fleet. Previously, the Pentagon had a stated goal of maintaining 44 operational GBIs. Adding two would...