The United States, the other sovereign members of the nuclear club, and a number of would-be proliferators have now entered what has been described as the “second nuclear age.” This paper examines the deterrence and defense requirements presented by this new age, arguing for the value to be gained through their integration. Offense-defense integration will provide to national decision-makers timely and informed choices of security options needed to address the spectrum of conflict likely to unfold within the second nuclear age.