SIMI VALLEY, CA -- Defense Secretary Mark Esper called on Defense Department leaders to make "tough choices" in cutting legacy systems and investing in new technologies as DOD eyes the end-game in building its fiscal year 2021 budget request. During the keynote address at the annual Reagan National Defense Forum here, Esper said “winning future battles” requires DOD to develop and deploy “new warfighting doctrine,” including multidomain operations and command-and-control across all domains, including space and cyberspace. “It requires us...