In thinking about how to support the twin goals of deterrence and assurance, the Obama administration has been struggling with how best to integrate U.S. nuclear weapons, conventional forces and missile defenses into a coherent strategic posture. Now budgetary pressures are making the trade-offs involved in striking the necessary balance for such an initiative even sharper.
These three military tools interact in complex ways. Nuclear forces are very powerful but for the most part unusable due to their destructiveness and the taboo associated with their use. Their main value is therefore to deter adversaries and reassure allies, thereby helping to avert wars, arms races and further horizontal nuclear proliferation. Conventional forces are the easiest to employ but are more constrained by budgetary and other resource limitations. Finally, ballistic missile defenses (BMD) have become increasingly prominent as a means to supplement the reassurance function of nuclear weapons. For this reason, they have enjoyed support from the Obama administration, despite the skepticism that many of its members had previously expressed toward BMD technologies.
Another challenge facing U.S. strategic policymakers is how to balance the deterrence and reassurance functions of U.S. military power with the possible negative effects U.S. capabilities can have when they evoke concerns in other countries. For example, while U.S. missile defense deployments are reassuring to U.S. friends and allies in Europe, Asia and the Middle East, they have been met with alarm in Russia, China, Iran and North Korea. Policymakers in these countries worry that the U.S. could become more confrontational and U.S. allies more emboldened if they came to believe that BMD systems could negate the missile arsenals of adversary states. These countries might respond by building up their own nuclear forces in response, with the resulting negative security spiral possibly triggering an arms race and a net decline in regional security.