The impact of strategic defenses on stability is a central theme in the Strategic Defense Initiative debate. This report examines the effects of defenses on first-strike stability. It is principally concerned with assessing first-strike stability during the transition from an offense-dominated strategic balance to a defense-dominated balance. It also examines the implications of various offensive and defensive force structures. The findings suggest that (1) first-strike instability during the defense transition can be minimized by careful force planning; (2) the most stable defense transition occurs when the ballistic missile defense transition is completed before significant levels of air defense are deployed; (3) arms control efforts will not necessarily reduce potential first-strike instabilities unless each side's counterforce capability is reduced; (4) asymmetries in each side's ability to suppress the opponent's defenses can lead to instabilities during, and after, the defense transition; and (5) biased perceptions make the defense transition either more or less stable, depending on the nature of the bias.

As ballistic missile technology proliferates, and as ballistic missile defenses are deployed by both the Russian Federation and the United States, it is increasingly important for these two countries to seek ways to reap the benefits of systems that can protect their own national security interests against limited missile attacks from third countries without undermining the strategic balance that the two governments maintain to ensure stability. Regional Ballistic Missile Defense in the Context of Strategic Stability examines both the technical implications of planned missile defense deployments for Russian and U.S. strategic deterrents and the benefits and disadvantages of a range of options for cooperation on missile defense.

Bringing together proponents and opponents of the Strategic Defense Initiative, this book includes original essays by leading experts on every aspect of the issue. The collection provides a valuable introduction to the many complex questions involved in any serious consideration of the SDI. The contributors explore such issues as the strategic impl

A pressing issue facing the United States in the early 1990s centers on whether, and for what strategic purposes, the United States should deploy nationwide ballistic missile defenses (BMD). One argument is that such defenses could enhance stability. This report extends the methodology developed in R-3765 to assess the effect of BMD deployments on first-strike stability. The authors conclude that (1) first-strike stability is currently robust; (2) deployment of strategic nationwide BMD by either superpower in competition with the other's strategic offenses generally erodes first-strike stability; (3) there might be a level at which U.S. and Soviet BMD could effectively defend against third-country ballistic missile attacks, unauthorized attacks, and accidental launches, without being so robust that it would undermine first-strike stability; (4) the buildup of U.S. defenses during Phase I deployment seems to exceed this level; and (5) maintaining effective bomber forces on both sides would be critical to any attempt to move from offense dominance to defense dominance.

First-strike stability between two adversaries is robust when both leaders perceive no great difference between the expected 'cost' to each side of striking first and the expected 'cost' of incurring a first strike if one withholds his attack. Conclusions include: (1) First-strike stability is currently quite robust. (2) Deployment of strategic nationwide ballistic missile defenses by either superpower in competition with the other's strategic offenses generally erodes first-strike stability. (3) Neither country would be likely to continue to adhere to agreements that constrain and reduce offensive arms under the specter of intent by the other to deploy robust strategic defenses in contravention to the 1972 Anti-Ballistic Missile (ABM) Treaty. (4) There may be a 'window' in which United States and Soviet strategic nationwide BMD could be robust in defending against 'limited' attacks (third-country ballistic missile attacks, unauthorized attacks, and accidental launches), yet not so robust that first-strike stability is seriously undermined. (5) The level of U.S. defenses attributed to the so-called 'Phase I' deployment seems to go beyond the upper bounds of this 'window' even with current offensive forces, and certainly with offensive forces constrained by START I. (6) Any attempt to transition to a situation in which each side's strategic defenses dominate the opponent's ballistic missiles must include a careful negotiation on the critical role of bomber forces in maintaining firs-strike stability.

First, technology is moving forward, making strategic defenses appear to be a more cost effective option than there were in the 1960s. Second, were we able to obtain a significant advantage over the USSR in strategic defenses, we could have a substantial measure of strategic superiority over them. Third, if both sides deploy significant strategic defense capabilities, the nature of the offensive force balance will become even more important than it is today; in particular, strategic force vulnerabilities that are worrisome today could prove disastrous for stable deterrence in a world that includes robust strategic defenses. Fourth, this picture would be sharply changed should strategic defenses themselves prove vulnerable, for this might create the first strike in space that would decisively alter the balance of forces on earth. Fifth, strategic defenses are likely to call NATO's strategy of diliberate nuclear escalation into even deeper question than it is today. The U.S.R & D program should be based on three criteria: First, our program should hedge against a Soviet breakout of the ABM Treaty and--in the longer term--against Soviet deployment of space-based defensive systems. Second, we should be looking for weapons concepts that will provide for quantum increases in capability and quantum reduction in cost. Finally, our technology programs need to be conducted with a view toward survivable defenses, especially for their spacebased components.

Should the US deploy ballistic-missile defences? The arguments for and against are becoming increasingly polarised. This paper offers what is currently lacking in the debate: a quantitative analysis of how well defences would have to work to meet specific security objectives, and what level of defence might upset strategic stability.