The history of warfare has been a struggle between offense and defense, with sometimes one side having the upper hand, and sometimes the other. The development of nuclear weapons seemed to demonstrate that for the very first time, an offensive weapon existed for which there was no effective defense. SDI (Strategic Defense Initiative), however, could be the answer. Using either orbital laser weapons, or thousands of missile-launched "Brilliant Pebbles," which are intended to collide with nuclear-tipped missiles in mid-air, SDI DEFENSE offers the real possibility of negating the threat posed by nuclear missiles.