The F-35 Lightning II is the result of the Department of Defense's Joint Strike Fighter (JSF) program, which sought to build a multirole fighter optimized for the air-to-ground role with secondary air-to-air capability. The JSF requirement was to meet the needs of the Air Force, Navy, Marine Corps and allies, with improved survivability, precision engagement capability, and reduced life cycle costs. The core engine, canopy, radar, ejection system, subsystems, and avionics are all common among the three different versions.