The White House has thrown down the latest gauntlet in a simmering conflict between Senate lawmakers and the Pentagon over acquisition reform proposals championed by Sen. John McCain (R-AZ) that would strengthen the role of military service chiefs at the expense of Defense Department civilians currently responsible for the process. McCain, who is chairman of the Senate Armed Services Committee, crafted a fiscal year 2016 defense authorization bill that, among other measures, calls for giving military service chiefs milestone decision...