BMD and Strategic Instability

In his "star wars" speech of March 23, 1983, in which he launched the Strategic Defense Initiative (SDI), President Reagan called for an effort to develop a defense against ballistic missiles which would change the basis of national security policy in a fundamental way. Instead of relying on the threat of punitive damage as a means of deterring the use of nuclear weapons against the United States and its allies, the SDI aims at preventing their delivery, through the development and deployment of active defenses. In calling for a defense that would render nuclear weapons "impotent and obsolete," the president was wittingly or unwittingly implying not only a 100-percent effective defense against ballistic missiles, but comple mentary and equally effective defenses against all other means of delivery of nuclear weapons as well?a point that was subsequently made explicit by Secretary of Defense Caspar Weinberger. President Reagan's goal of a perfect defense stirred the interest of the general public and of many public figures who have long sought an alternative to deterrence based on mutual assured destruction