There are many different potential challenges to living with a nuclear Iran. A number lie in the broad realm of strategy or even grand strategy: preventing further proliferation, maintaining the stability of the region, and forestalling any shift in the balance of power toward Iran. The tactics and mechanics of deterring a nuclear Iran will present their own difficulties that must also be addressed, and addressed in a concrete and immediate fashion.
The logic of nuclear weapons, as Bernard Brodie first described it at the dawn of the nuclear era, is certainly compelling and lends a considerable amount of strength to nuclear deterrence. But as numerous Cold War crises demonstrated, such logic can be undermined—potentially fatally—by faulty implementation, poor communication, misperception, malign intent, and excessive ambiguity or excessive specificity.
Getting deterrence right between two responsible, mostly status quo powers that knew each other fairly well—like the United States and Soviet Union—was hard enough and nearly resulted in tragedy on several occasions. Doing it with a country like Iran—whose political system is utterly opaque and unpredictable even to its own members— or between two countries like Iran and America—whose entire history has been one of constant misunderstanding—is going to be harder still.
A preliminary exploration of some of the most salient military-technical aspects of a deterrence regime should Iran acquire a nuclear weapons capability in the near future necessarily raises more questions than it answers. Even the answers it provides should be considered tentative and merely a starting point for additional study and debate.