Historically, research in the area of warfare has seen the development of powerful new weapons closely followed by the development of defenses to counteract the weapons' destructive power. The development of nuclear weapons seemed to be the exception to this rule: for the first time, mankind had created a weapon to which there was apparently no effective defense. SDI (Strategic Defense Initiative), however, could be the answer to this problem. Using laser-equipped orbital satellites or ground-launched ABMs (Anti-ballistic Missiles) to intercept and destroy enemy nuclear missiles in mid-air, the SDI Defense offers the first hope of negating the threat posed by nuclear missiles.