The third possible outcome of the standoff is that Iran continues its current course and publicly goes nuclear by testing a weapon. U.S. and Israeli officials have declared that outcome unacceptable, arguing that a nuclear Iran is a uniquely terrifying prospect, even an existential threat. Such language is typical of major powers, which have historically gotten riled up whenever another country has begun to develop a nuclear weapon of its own.

Yet so far, every time another country has managed to shoulder its way into the nuclear club, the other members have always changed tack and decided to live with it. In fact, by reducing imbalances in military power, new nuclear states generally produce more regional and international stability, not less.

Israel's regional nuclear monopoly, which has proved remarkably durable for the past four decades, has long fueled instability in the Middle East. In no other region of the world does a lone, unchecked nuclear state exist. It is Israel's nuclear arsenal, not Iran's desire for one, that has contributed most to the current crisis. Power, after all, begs to be balanced. What is surprising about the Israeli case is that it has taken so long for a potential balancer to emerge.