Multipolar nuclear stability: Incentives to strike and incentives to preempt

First strike stability, or incentive to preempt in a strategic nuclear environment, underlies many discussions of strategic force structure, posture, and arms control. In the bipolar context it is generally agreed that defenses are destabilizing, particularly at medium to high levels. The impact of additional armed sides on stability, however, is not well understood. The objective of this paper is to shed light on this multipolar stability question, particularly on the stability implications of small-to-medium size defenses.