The U.S. Air Force is one step closer to replacing its worn-out fleet of Northrop Grumman E-8C Joint Surveillance Target Attack Radar System (J-Stars) tank hunters after beginning a $6.9 billion competition to develop and deliver 17 replacements based on a “smaller and more efficient airframe.” The radar-carrying E-8C was designed in the 1980s and delivered through the ’90s for ground surveillance, battle management and command-and-control missions.