Toning Up the Nuclear Triad

How each leg of America's strategic deterrent really works

In the 40 years since the Enola Gay, a B-29 long-range medium bomber, dropped its atom bomb over Hiroshima, America's nuclear-weapons systems have evolved into what has been known for the past 25 years as the Triad. The name comes from the fact that U.S. strategic nuclear weapons are based in the water, on land and in the air. Defense strategists agree almost universally that all three legs of the Triad are essential because each by itself has weaknesses that are offset only by the strengths of the other two. Land-based intercontinental ballistic missiles (ICBMs), for example, are the most accurate...