BRINGING THE THUNDER (STEALTHILY) A B-2 Spirit bomber, with stealth capabilities that can penetrate the most secure defense systems, taxies on a flightline in October 2014 during Exercise Global Thunder 15. Innovation doesn’t happen in a vacuum: The U.S. military didn’t innovate stealth capabilities for the heck of it, but because the existing solutions to the problem of Soviet air defenses were expensive and imperfect. (U.S. Air Force photo by A1C Joel Pfiester, 509th Bomb Wing Public Affairs Whiteman Air Force Base)