The Missile Defense Agency is now betting on a service life extension project to improve the Ground-based Midcourse Defense system until the Next Generation Interceptor is ready for fielding, a shift in messaging from the agency's gambit last year that proposed an underlayer featuring new variants of the Aegis and Terminal High Altitude Area defense systems. MDA Director Vice Adm. Jon Hill said GMD SLEP is how the U.S. military plans to keep up with North Korean long-range missile advances...