"This Note provides a background against which to evaluate possible Soviet alternatives for dealing with the Strategic Defense Initiative (SDI) in the decade ahead. Without speculating about what the Soviets will ultimately do in response to SDI, the Note (1) examines Moscow's statements on SDI to date, (2) reviews the highlights of Soviet doctrine and programs related to strategic defense, (3) considers the real concerns that may underlie the Kremlin's public posturing on SDI, and (4) outlines the key political and strategic factors that will constrain the Soviets' eventual response. The author suggests that, assuming SDI does lead to a deployable U.S. ballistic missile defense, the Soviets will be driven to counter that threat within the limits of their economic and technical resources. Forecasting the technical details of their response at this time, however, is complicated by uncertainty not only about Soviet concerns, motivations, and intentions, but also about what the United States will eventually do with SDI."--Rand abstracts.