 Some tactical nuclear weapons have specific features meant to enhance their battlefield characteristics, such as variable yield, which allow their explosive power to be varied over a wide range for different situations, or enhanced radiation weapons (the so-called "neutron bombs"), which are meant to maximize ionizing radiation exposure and to minimize blast effects.Strategic missiles and bombers are assigned preplanned targets including enemy airfields, radars, and surface to air defenses, not only counterforce strikes on hardened or wide area bomber, submarine, and missile bases.The strategic mission is to eliminate the enemy nation's national defenses to enable following bombers and missiles to threaten the enemy nation's strategic forces, command, and economy more realistically, rather than targeting mobile military assets in nearly real time by using tactical weapons that are optimized for time sensitive strike missions that are often close to friendly forces.