In April 1961, one of the seminal think-pieces on proliferation appeared. This was Albert Wohlstetter's famous Foreign Affairs article analyzing the so-called "N + 1" problem. This formulation was Wohlstetter's way of characterizing the next incremental addition to the existing number of nuclear weapons states. In an elegant analysis focused mainly on the nuclear problem in Europe, he argued that the U.S. nuclear umbrella was the answer to the security needs of NATO's potential next nuclear states. He argued further that disarmament would only fuel Soviet ambitions, but that export controls and modest arms control measures had a role to play in limiting nuclear diffusion.
In this, as in so many other areas, Wohlstetter's ideas helped to shape his generation's thinking about the proliferation problem. But wholly new factors have arisen over the past four decades, and we need to think differently about the issue because the problem itself has changed. We can best see how it has changed by taking separately the two parts of Wohlstetter's simple "N + 1" expression.
First is the "N" factor: the number of existing nuclear-armed states. Today, the policy debate remains focused on the challenge of preventing those two or three states most desirous of joining that number from achieving their ambition. Now, as then, nuclear proliferation presents risks of major importance for international stability and U.S. security. The emergence of a nuclear-armed Iraq, Iran, or North Korea would be deeply unsettling, both regionally and globally. So too would be the leakage of nuclear weapons materials, technology, or expertise to both state and non-state actors. Stopping such proliferation remains a top policy priority, as it was in 1961.
