The Defense Department marked a landmark achievement in the decades-long effort to develop the Ballistic Missile Defense System during an operational flight test above the Pacific Ocean today, intercepting an intercontinental ballistic missile-class target as part of a key assessment of the Ground-based Midcourse Defense system. The May 30 test marked a first-ever attempt to intercept an ICBM target -- designed to represent a threat, with countermeasures, that U.S. intelligence believes North Korea or Iran could one day field --...