The Defense Department is preparing to send lawmakers findings of an independent technical study on the feasibility of using an unmanned aerial vehicle to launch an interceptor against a North Korean intercontinental ballistic missile during the first minutes after launch. The Missile Defense Agency, in response to a statutory mandate, last year tapped the MITRE Corp. to assess a 2017 study by the Science, Technology and National Security Working Group of the Massachusetts Institute of Technology titled "Airborne Patrol to...