AbstractAlvin Weinberg has contributed substantially to the debate over strategic nuclear weapons policy on averting nuclear war. His views over the past 25 years have been remarkably consistent, involving a strong preference for combining defensive systems with offensive disarmament. These principles have placed him at odds with the core of conventional strategic thought in this country, which has argued against the construction of defenses. President Reagan’s“Star Wars”proposal, however, has led to a rethinking of fundamental first principles, and reintroduced the possibility of defenses. Weinberg’s latest contribution to this debate, something he calls“Defense-Protected Build-down,”has the potential to be quite influential in guiding future strategic thought.