In the hands of an adversary, an Islamic bomb is concrete evidence that Iran's strategy of "resistance" to the West is a winning one. And this will change the region's political culture from radical to many times more radical.
At best, this means that even those U.S.-friendly regimes that have much to fear from "resistance" will have no choice but to raise the pitch of their anti-American rhetoric to stay in step with their rivals—and their populations. Consequently, the basing rights that we have throughout the Gulf states are likely to be terminated.
At worst, an Iranian bomb sends a message to the more ambitious actors in the region that they should feel free to make a run at the Americans. If Tehran showed it is less profitable to play nicely with Washington than it is to extort the Americans and kill their soldiers (as Iran did in Iraq and Afghanistan) and allies (as Iran did in Lebanon and Israel), why shouldn't they do the same? We will not be deterring Iran but inviting the rest of the region to shoot at us.
The one ally that shares our interests and is capable of defending them against Iran and its assets is Israel. Containment requires that the superpower persuade its allies that they should put aside local concerns and look at the big picture; but in this case it is Israel that is focused on Iran while the Obama administration has pecked away at the Netanyahu government over settlements. In Cold War terms, that is as though President Ronald Reagan had directed his "tear down this wall" speech not to Soviet leader Mikhail Gorbachev but to West German Chancellor Helmut Kohl. Instead, Reagan put Pershing missiles at Kohl's back and pointed them at Moscow.
Still, it is worth noting that our position will not necessarily be secured by an Israeli strike on Iran, for there are some things that need to be done by the alpha dog. Soft power, or what used to be called prestige, is effective only in proportion to how much our hard power is feared by enemies and prized by allies. If we leave Iran to Israel, we are enhancing Jerusalem's prestige at the expense of our own.
At least all the talk of deterrence and containment should remind us why we fought the Cold War: to protect our way of life, a life sustained by oil. Without cheap oil, the life we came to associate with peace would not have been the same. The Persian Gulf was the Cold War's strategic grand prize, and that we have held onto it for 65 years is a credit to the design of Washington's policy of preventing any adversary from breaking out with just the sort of game-changing threat that the Iranian nuclear program represents. In other words, the American order of the Middle East is containment; its unraveling will not allow for a different form of containment but spells the end of our hegemony in the region.
Human history is nothing but the record of nations that have miscalculated their capacity to project power, the willingness (and ability) of their allies to support them, and the determination of their rivals to reshape the world after their own image. As the debate over Iran policy has devolved from strategy to pop psychology—as, for example, in the discussion of whether the Iranians are acting rationally or whether their apocalyptic rhetoric suggests they will do anything to hasten the Mahdi's return—the fact is that no regime consciously wishes to bring its own existence to an end. And yet states and regimes do nonetheless cease to exist. No sane person believes that the United States is suicidal, but if a nation will not or cannot defend its way of life, it has taken the first step toward its inevitable decline, which is tantamount to suicide.