First, we're not talking here about a one-off raid, but a sustained air campaign against numerous hardened sites. We may need Special Forces or ground troops to verify that the nuclear facilities have in fact been destroyed.
Second, it's hard to see Iran backing down in the face of an air campaign, and submitting to a program of intrusive inspections. More likely they will retaliate, against Israel, or in the Persian Gulf, escalating the war. The campaign, for example, may require operations against Iranian naval vessels to protect oil routes.
Third, once the bullets start flying, American opinion would probably shift in favor of escalating the war and fighting for regime change. In wartime, Americans often see the struggle as a crusade to punish evil and protect freedom and democracy--requiring the grandest of objectives.
The 1861-65 Civil War began as a limited campaign for reunion, and ended as a righteous cause to emancipate the slaves.
The same story held true in the 1898 Spanish-American War, which started out as a mission to free Cuba from Spanish rule, and concluded with the conquering of Puerto Rico, Guam, and the Philippines.
The United States entered World War I in 1917 in large part to protect its neutral rights, and ended the war fighting a crusade to make the world safe for democracy.
In World War II, Americans started out supporting majestic war aims including unconditional surrender and regime change--and these goals became more strongly entrenched over time.
The original objective of the 1950 Korean War was to save South Korea from invasion, but soon enough, American soldiers were on the march, fighting for regime change in North Korea.
But wasn't the 1999 Kosovo War restricted to airpower? Yes--but only just. When the campaign started in March 1999, Clinton ruled out
the use of ground troops. By June, however, NATO forces were actively preparing for an invasion of Serbia, before Milosevic suddenly caved.
In any case, battling a demonized theocratic enemy in Iran, intent on wielding nuclear weapons, would stir America's crusading spirit far more than a humanitarian war to save Kosovo Albanians.
So Obama would have two options. He could keep the Iran War restricted or he could escalate. If the president limited the goals of the war, he would face fierce resistance from frustrated hawks. After all, if the Iranian regime is such a grave danger that military action is required, how can the theocrats be allowed to stay in power?
Consider the example of the 1991 Gulf War. Bush senior decided to fight a limited war to liberate Kuwait. Once Desert Storm began, however, well over 70 percent of Americans wanted to escalate the war and overthrow Saddam Hussein. By 1992, 69 percent of Americans thought that the Gulf War wasn't a victory because Saddam was still in charge.
Phase IV: Quagmire
What if U.S. troops end up marching on Tehran? Here, public support would probably hold up until the Iranian regime collapses. There may even be a brief moment of exhilaration as American forces reach the capital. When the statue of Saddam fell in Firdos Square, Baghdad, on April 9, 2003, Brit Hume declared on Fox News: "this transcends anything I've ever seen." Pictures of the toppling of the statue were shown repeatedly all day (once every 4.4 minutes on Fox from 11 a.m. to 8 p.m.).
But as the so-called "Pottery Barn Rule" goes, "You Break It, You Own It." The Iran War would shift to a nation-building and counter-insurgency operation. Whatever course the stabilization mission took, Americans would very likely see it as a failed quagmire. The United States has engaged in dozens of nation-building operations in its history, from southern Reconstruction after the Civil War, to Somalia. Virtually every mission was seen as a debacle. If you like nation-building in Afghanistan and Iraq, you'll love nation-building in Iran.
Phase V: Regret
The war is likely to end in regret. Obama would be damned if he limited the campaign to air strikes, and damned if he escalated and fought for regime change. Any restricted operation that left the regime in power might face criticism from a growing lobby of hawks. Meanwhile, regime change means nation-building, and stabilizing Iran would be about as popular as stabilizing Iraq.
So, whether we're looking at Truman and Korea, LBJ and Vietnam, Reagan and Lebanon, Clinton and Kosovo, George W. Bush and Iraq, or Obama and Afghanistan, the pattern is clear: war rarely pays a long-term political dividend. Even military success does not guarantee much domestic benefit. President George H. W. Bush won convincing victories in Panama in 1989 and in the Gulf War in 1991, and then promptly lost his bid for re-election against Clinton in 1992.
Military failure against Iran would be politically catastrophic for Obama. At the same time, it's not clear that success on the battlefield would offer much of an enduring advantage. War could give a short-term boost to Obama's approval ratings, but in the long-term, it would be more likely to destroy his presidency than save it.