The challenge for Israel in responding militarily to Iran’s nuclear weapons program is that Israel has the capacity to start a conflict, but not to conclude it (save through the use of its own nuclear arms—an unlikely scenario, for now). Israeli airpower and missile forces could frustrate Tehran’s ambitions for a period of a few and perhaps several years, but it would prove a Pyrrhic victory, given Iran’s inevitable response.
Were Israel to strike (with the expected collusion of Saudi Arabia), Iran certainly would attempt to hit back directly at Israel, employing long-range missiles as well as “unleashing” Hezbollah. But that would be a necessary gesture, not the main axis of retaliation. In the wake of an attack, Tehran would respond asymmetrically by closing the Strait of Hormuz and attacking shipping in the Persian Gulf; by conventional attacks on oil storage, processing, and loading facilities along the Arab littoral of the Gulf; and by direct attacks on Saudi and other Gulf oil fields.
The immediate purpose would be to demonstrate resolve and inflict graphic damage on regional rivals, but the greater purpose would be to punish the global economy by disrupting oil and gas supplies and—of even greater importance—exciting an international financial panic that spread pain broadly.
The Iranians are incisive strategic thinkers and realize that they would not receive the primary blame for such a response; quite the contrary, the “international community,” with its reflexive, complex, and bitter distaste for Israel, would censure Jerusalem and Tel Aviv, not Tehran. The master strategists in Iran understand how dearly much of the world longs for an excuse to abandon Israel as a cause and punish it as an aggressor.
For the United States, the scenario would be grim. Although Israel began the conflict, we would need to finish it. This would be a significant and costly endeavor, lasting months, at a minimum, and it would be waged in the face of divided global opinion, with the majority of states disapproving of our action and pressing for a premature end to any military campaign.
The potential for such a conflict spreading regionally or even beyond is great. And Israel would suffer grievous physical harm (from Hezbollah and Hamas attacks) but even greater diplomatic damage. Israel, not Iran, would emerge as the pariah among states.
The unappealing bottom line is that, should it be necessary to interrupt Iran’s nuclear-weapons program with military force, it would be better done by a U.S.-led coalition or even by the U.S. unilaterally. And such a campaign would need to be comprehensive and ruthless if it were to disable Iran’s retaliatory potential. Targets would need to go well beyond Iran’s nuclear infrastructure.
In short, best for the U.S. to do what needs to be done, but better to do nothing than to employ military forces haltingly. Any small-scale attack would result in a large-scale disaster.