Under Reagan SDI explored advanced technologies with the aim of determining the feasibility of effective, nonnuclear ballistic missile defenses (BMD). The initial focus of SDI reflected US concerns about growing Soviet first-strike capabilities. Thus, an initial deployment of defenses, or Phase I Strategic Defense System, was to have provided the minimum defensive capability that would add meaningfully to deterrence of a Soviet first strike. However, with the end of the [[Cold War]], President [[George H.W. Bush]] in early 1991 directed that SDI be refocused to provide global protection against limited strikes, thus shifting the primary US role for BMD from deterrence to actual protection. | Under Reagan SDI explored advanced technologies with the aim of determining the feasibility of effective, nonnuclear ballistic missile defenses (BMD). The initial focus of SDI reflected US concerns about growing Soviet first-strike capabilities. Thus, an initial deployment of defenses, or Phase I Strategic Defense System, was to have provided the minimum defensive capability that would add meaningfully to deterrence of a Soviet first strike. However, with the end of the [[Cold War]], President [[George H.W. Bush]] in early 1991 directed that SDI be refocused to provide global protection against limited strikes, thus shifting the primary US role for BMD from deterrence to actual protection. |