First-Strike Stability and Strategic Defenses

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.