The likelihood of direct military conflict between the U.S. and its top adversaries is growing, fueled by deepening strategic cooperation between China, Russia, North Korea and Iran, according to the head of North American Aerospace Defense Command and U.S. Northern Command. Air Force Gen. Gregory Guillot warned that these adversaries are expanding their military capabilities and strengthening ties in ways that directly threaten the U.S. homeland in Feb. 13 written testimony prepared for the Senate Armed Services Committee . He...