Among national security experts there is nearly universal agreement on the following: Bombing could set Iran's nuclear program back by one or two years, maybe even several, but it would also (1) remove any doubt in the minds of Iranian leaders about whether to pursue nuclear weapons; and (2) ensure that the Iranian nuclear program was revamped to resist future air strikes.

And the new, more entrenched Iranian nuclear program wouldn't be the kind of thing that could be undone by a new generation of bunker-buster bombs. According to experts I've talked to, Iran would probably react to bombing not by burying its nuclear facilities deeper, but by dispersing them much more widely. They would be impossible to identify from the air and for that matter not readily identifiable from the street. Meanwhile, the international inspectors who now keep us apprised of Iran's nuclear status would be banned in the wake of air strikes. So even if we were willing to make additional bombing runs on an annual basis ("mowing the lawn," as some call it), we could never be confident that Iran wasn't producing a nuclear weapon. The only path to such confidence would be to invade the country and seize the instruments of state.

Would we actually do that? Probably. In justifying the initial bombing, President Obama will have driven home how unacceptable an Iran with nuclear weapons is, thus establishing as a kind of doctrine that America will never let Iran acquire them. (The "Obama doctrine" has never acquired a clear meaning, and I'm sure some hawks would be happy to assign it this new one as a way of gluing Obama to his commitment.)

Doctrines can be abandoned, of course, but only at some political cost. And this one would be an especially unlikely orphan when you have a president who (being a Democrat) is insecure about his national security credentials and, on top of that, is insecure about his pro-Israel credentials. Of course, if Obama loses in November, then, one or two years down the road, it won't be the creator of this doctrine who is in the White House. But in the event of a Republican presidency, adherence to such a doctrine is pretty much assured anyway. (See first paragraph, above.)

But why take my word for any of this? I'll close with the judgment of now-retired four-star Marine Gen. James Cartwright. Two years ago, when he was Vice-Chairman of the Joint Chiefs of Staff, he had this exchange with Sen. Jack Reed during Senate hearings:

Senator Reed: I presume that [a bombing campaign] would not be 100 percent effective in terms of knocking them out. It would probably delay them, but that if they're persistent enough they could at some point succeed. Is that a fair judgment from your position? General Cartwright: That's a fair judgment. Senator Reed: So that the only absolutely dispositive way to end any potential would be to physically occupy their country and to disestablish their nuclear facilities. Is that a fair, logical conclusion? General Cartwright: Absent some other unknown calculus that would go on, it's a fair conclusion.