Book excerpt: As ballistic missile technology proliferates, and as ballistic missile defenses are deployed by both the Russian Federation and the United States, it is increasingly important for these two countries to seek ways to reap the benefits of systems that can protect their own national security interests against limited missile attacks from third countries without undermining the strategic balance that the two governments maintain to ensure stability. Regional Ballistic Missile Defense in the Context of Strategic Stability examines both the technical implications of planned missile defense deployments for Russian and U.S. strategic deterrents and the benefits and disadvantages of a range of options for cooperation on missile defense.