The United States is planning to modernize its strategic nuclear deterrent for the first time since the Cold War ended over thirty years ago. The deterrent comprises three main components, or “legs”: land-based intercontinental ballistic missiles (ICBMs), distributed in hardened silos throughout the northern Midwest; fleet ballistic missile submarines (SSBNs) operating from two bases, one on each coast; and long-range bombers positioned at three air bases in the continental United States. These three legs are known collectively as the triad.

This study analyzes the United States’ plans for modernizing the land, sea and airborne legs comprising its strategic nuclear force triad. This force has been charged primarily with deterring a nuclear attack on the United States, its allies, and security partners (“extended deterrence”), and mitigating the consequences should deterrence fail.