This pamphlet presents a discussion of the various components of President Reagan's Strategic Defense Initiative (SDI) including the problem of pulling together various new technologies into an effective defensive system and the politics of the so-called "star wars" system. An important part of the defense initiative is the "layered" defense system in which star-wars weapons attack nuclear warheads at four phases of their 30-minute trip from silos to U.S. territory. One of the major weapons discussed is the railgun being developed at the Army's weapon design facility in Dover, New Jersey. This weapon uses bursts of electricity instead of gunpowder. At first the star-wars system would likely rely on railgun projectiles and warheads on fast rockets, both of which get their destructiveness from kinetic energy, the energy of motion. Another type of kinetic energy weapon that is much more technologically mature is the lightening-quick rocket interceptor. The U.S. military now has a wide range of such rockets in its arsenal, including shoulder-fired anti-aircraft Stingers, the Sidewinder, and the recently tested Air Force anti-satellite missile. These could be used to attack ballistic missiles and warheads in space. SDI officials do not see development of a practical and affordable beam weapon system occurring this century. Many technological advances are being made in the SDI program, but it may be near the turn of the decade before those working on SDI can say whether a working system can be developed. A series of questions designed to stimulate classroom discussion concludes the document. (SM)