The last decade has not been a happy time for US defense planners. During these years, they have witnessed a profound and ominous expansion and modernization of Soviet nuclear and conventional military capabilities. At the nuclear level, the Soviet Union has deployed the SS-17, -18, and -19 intercontinental ballistic missiles (ICBMs) with multiple, independent reentry vehicles (MIRVs) which rival the accuracy of the most modern US Minuteman III. Moreover, the larger yields of the Soviet warheads have led many planners to fear that the Soviet Union is rapidly approaching and, indeed, may now possess the ability to deliver a debilitating strike against the land-based leg of the US strategic Triad—which has been instrumental in the postwar period in preserving peace by deterring nuclear conflict.