The Quadrennial Defense Review will likely revamp the Pentagon's profoundly influential requirement to prepare for two concurrent wars by dropping the second major combat operation while insisting U.S. forces juggle an array of smaller but still substantial operations worldwide, according to defense and military officials. Given the enormity of the challenge in Iraq and Afghanistan, the two-MCO construct that emerged in the early 1990s is seen by Defense Secretary Robert Gates and others at the Pentagon as unrealistic. Details of...