Summary and Conclusion
As with the Alliance debates over flexible response in the 1960s, the current debate over SDI should prove to be both interesting and provocative as it may portend an evolution in NATO strategy even more significant than the shift from massive retaliation to flexible response. The significant and controversial nature of the SDI issue stems from the fact that it forces the Alliance to reevaluate some of the core premises of its security policy in the nuclear age. It especially spotlights the problematic viability of both NATO's central strategic concept of flexible response and its central component, the U.S. strategic nuclear guarantee. This is not to say that SDI is the cause of NATO's strategic problems; indeed, SDI may well provide some of the answers to problems caused by the structural division over NATO nuclear strategy that continues to plague the Alliance.
The INF Treaty adds a new dimension to Alliance considerations of strategic and theater missile defenses. The removal of U.S.Pershing II and GLCMs is sure to limit NATO's nuclear flexibility, though by how much is as yet uncertain. At the very least, the removal of INF will impose greater demands on U.S. strategic nuclear forces and on NATO's conventional capabilities at a time when these balances greatly favor the Soviet Union. To the extent that missile defenses can strengthen the U.S. strategic nuclear guarantee and preserve NATO flexibility at the conventional and theater nuclear level, BMD and ATM would be a welcome contribution to NATO's deterrent capabilities.
A major conclusion of this study is that when considered in the context of present and projected instabilities in the strategic environment, SDI--and, indeed, the deployment of ballistic missile defenses--is imperative for Western security. Western European critics of SDI, however, would tend to disagree with this conclusion, adducing that the present deterrence regime,