Michael Crowley expresses shock over a new Pew poll finding that 61% of Americans would favor military action to prevent Iranian development of nuclear weapons if other options fail. 

I'm less shocked.  In the run-up to the Iraq War, the belief that Saddam Hussein had developed or was rapidly developing WMD, including nuclear weapons, was a pretty important factor in the robust majorities that favored military action.  And the discovery that he actually didn't have WMD helped turn Americans against the war once his regime had been toppled.  Since evidence of an Iranian nuclear program is far better established, it's not that shocking that Americans would react now as they did in 2002 and 2003. 

But the other big thing that obviously turned Americans against the Iraq War was the immense cost and difficulty of consolidating the initial military victory.  In the Pew poll, respondents are asked if they favor "military action."  It's entirely possible that many of those answering "yes" are thinking in terms of some "surgical strike" that will destroy the nuclear program without a wider war.  Should negotiations and/or sanctions fail and we are actually contemplating military conflict with Iran, it will more than likely become apparent that eliminating Iran's nuclear program will require an actual ground war aimed at regime change.  It's at that point when the lessons of Iraq will truly begin to sink in, and support for "military action" will go down.  But we haven't had that debate yet.

What the Pew poll does show is that Americans don't seem to buy the argument that a nuclear Iran is deterrable (by the United States or by Israel), just as the regimes of Stalin and Mao--and for that matter, Hitler, who had stockpiles of chemical weapons he didn't dare to use--were deterrable.  Perhaps that means that Americans, like many Israelis, view the current Iranian regime as uniquely dangerous, or at least frighteningly irrational, and capable of inviting unimaginable casualities in a nuclear exchange with Israel or the U.S.   Or perhaps they simply think a nuclear Iran would permanently destabilize the world's most fragile region.  But deterrance is inevitably a matter of calculated risks.  Had it been possible during the Cold War to "take out" the Soviet Union's or China's nuclear capacity without a calamitous war, a majority of Americans would have supported doing just that.  Once the costs and risks of war with Iran are fully aired and debated, some Americans now favoring "military action" may decide that Iran is deterrable after all. 

The fact remains that we haven't yet had the full debate that will ultimately shape U.S. policy towards Iran.  In the meantime, it's fine by me if Tehran reads about this Pew poll and reconsiders its current drive for nukes. 

Ed Kilgore is Managing Editor of The Democratic Strategist and a senior fellow at the Progressive Policy Institute.