Stephen Kinzer writes in the current issue of the New York Review of Books:
Consumed by the conflict in Iraq, the Bush administration has been unable to find either the political or military resources to deal with Iran, which poses both greater dangers and greater opportunities. That is fortunate. During the surge of messianic zeal that drove the Bush administration in its early days, there was heady talk about the prospect of “liberating” Iran as soon as the United States Army was able to break away from the waves of gratitude that were expected to engulf it in Baghdad. That fantasy collapsed when the Iraqi insurgency broke out.
If the Iraq invasion had gone as its planners expected, with the occupied nation embracing its conqueror and quickly transforming itself into a Jeffersonian paradise, American troops might well have been sent across the border into Iran. There they would have had to fight a huge army filled with people who detest the theocracy that tyrannizes them, but who also have a profound sense of patriotism, an ancient tradition of resistance, and a religiously driven thirst for martyrdom. Iraqis who rose up against the American occupation may have done the world, and especially the United States, a good turn by making an invasion of Iran all but impossible.