The retiring general in charge of NORAD and the U.S. Northern Command said Thursday that he's leaving behind no unfinished business but has concerns about the nation's aging radar system and jet-fighter fleet. Air Force Gen. Gene Renuart ends his 39-year Air Force career July 1. Since March 2007, he has overseen the North American Aerospace Defense Command, a joint U.S.-Canadian command that monitors air and space threats to both nations, and the Northern Command, which oversees the U.S. military's homeland defense and supports civilian authorities. The nation's current radar system needs to be updated with an integrated system of...