Projections of the rise and fall of nations form an indispensable element in the conduct of diplomacy, yet such estimates of what power is and how it is changing are very uncertain. Some observers, indeed, have suggested that we are nearly destined to get it wrong. The English statesman Henry St. John, Lord Bolingbroke, noted that those "who are in the sinking scale do not easily come off from the habitual prejudices of superior wealth, or power, or skill, or courage, nor from the confidence that these prejudices inspire. They who are in the rising scale do not immediately feel their strength, nor assume that confidence in it which successful experience gives them afterwards."

There are undoubtedly perils associated with either underestimating or overestimating one's power. The former mistake may lead to departures from an otherwise sound position or to a failure to exploit opportunities. The latter mistake is also familiar. History is littered with the examples of states that, acting on the "habitual prejudices of superior wealth, or power, or skill, or courage", undertake enterprises that prove the cause of their undoing. Though common sense suggests that these opposing traits would seldom be found together, historical experience often finds them joined at the hip. In Vietnam, for instance, both errors were committed. At the outset of American involvement, U.S. policymakers overestimated their ability to beat an ostensibly third rate power into submission and underestimated the true strength of the American position vis-à-vis the communist powers, mistakenly believing that if Vietnam turned communist the entire structure of peace would crumble.

The Bush Administration is committing the same dual error in its approach to Iran. It has vastly exaggerated the dangers associated with the development of an Iranian nuclear weapons program and underestimated the deterrent capacity of American military power. It has also vastly underestimated the potential perils of a preventive war against Iran.

Lessons of the Iraq War

One of the most remarkable features of the Iraq war is that it did not discredit the argument that preventive war must remain "on the table" as a way of preventing the proliferation of weapons of mass destruction. In the aftermath of the American invasion, when it was discovered that there were no weapons to be found, attention was focused instead on the colossal intelligence failure that lay behind the American effort. Mainstream critics made hay with an administration that had "stovepiped" intelligence to fit preconceived opinions, not with the underlying assumption that force would indeed have been justified had Iraqi WMD been found. Whether the administration deceived others or simply deceived itself became the vital question to disentangle, and Democratic critics looking to score political points did not directly challenge the underlying logic of the war.

The curious failure of the political opposition to meet the administration head on is also apparent in what emerged as the second great rationale for the Iraq war, which justified the enterprise as a noble crusade to depose a tyrant and to bring democracy to the Middle East. It is not exactly true to say that the administration switched rationales for the war once the banned WMD were not found, for the "we shall transform the Middle East by bringing democracy to Iraq" argument was present from the very outset, but it is undoubtedly true that the missing weapons did lead the administration to place far greater emphasis on the democratizing rationale. As with the argument over the weapons of mass destructions, critics in the main did not challenge the idea that bringing democracy to an oppressed people via external force was a noble and legitimate enterprise. Instead, they stressed the ham-handedness, lack of planning and operational errors that attended Operation Iraqi Freedom. Had Rumsfeld not displayed such hubris and had the advice of the generals for a larger force been heeded, they implied, it would all have worked out nicely in the end.

The Iraq War has become deeply unpopular with the American people, and only a third of the public approves of the Bush Administration's handling of the conflict. Despite these misgivings, however, it is remarkable that the swelling public disapproval has not really reached either of the two major rationales the administration adopted in making its case for the overthrow of Saddam Hussein. The critique has focused on operational execution rather than the great objectives of national policy. It is probably fair to say that any future war justified simply on the supposed benefits of extending democracy would have great difficulty commanding public support, for the anticipated costs of such an enterprise would likely be seen by the public as outweighing any potential benefits. But a war to prevent the proliferation of weapons of mass destruction is a much different proposition. This meets, or appears to meet, the security test that the public imposes on projected uses of U.S. military power.

John McCain's formulation--"there is only one thing worse than military action, and that is a nuclear-armed Iran"--may well reflect a majority in public opinion. He appears to be joined in that perception by the "national security Democrats" and their new spokeswoman, Hillary Clinton, who has argued that "We cannot and should not--must not--permit Iran to build or acquire nuclear weapons."

Despite the confident assertions that Iran is hell-bent on acquiring nuclear weapons, the evidence available supports a much more guarded conclusion. Iran's public position is simply to insist upon its rights under the Nuclear Non-Proliferation Treaty (NPT) to develop a civilian nuclear program, and it has offered to pair that acknowledgment with its acceptance of an intrusive inspections program. Its case for civilian nuclear power, though usually dismissed as transparently mendacious, is reasonably strong. Its reliance on oil for export earnings makes it reasonable to want diversification in its energy sector. Iranian public opinion--not simply the mullahs, but Western-leaning groups as well--bridles under the assumption that Iran is to be stigmatized and denied the rights common to all under the NPT. It is true that the development of a civilian nuclear industry, even accompanied by international inspections, would give Iran the capability to move more rapidly to the production of a bomb were the decision taken to do so. Still, the confident assertions that Iran has decided to acquire nuclear weapons and will bend every effort to do so is simply worst-case speculation dressed up as fact. An equally plausible reading of the evidence is that Iran would be content with the recessed nuclear capability that such a bargain--enrichment on Iranian soil combined with intrusive inspections--would provide them.

The consensus view that Iran could not be deterred if it did acquire nuclear weapons is also dubious in the extreme. These alarms were a regular feature of the Cold War, and it was confidently predicted that neither the Soviet Union nor China would be susceptible to deterrence once they acquired atomic devices. Events showed otherwise. It is said today that President Ahmadinejad is different, that he welcomes the coming of the twelfth imam that a nuclear holocaust would entail, and that a crazed religious fanatic in control of a nuclear-armed state would represent an intolerable danger to Israel, the Gulf sheikhdoms, the United States and the rest of the world. Against these considerations, however, it may be asserted that the Iranian public did not elect their new president on the basis of the expectation that they would soon be burnt to a crisp, but rather that he would improve their standard of living in the here and now; that Ahmadinejad's reputed common touch is utterly incompatible with the careless disregard for the lives of his countrymen that such an act would entail; that any decision for war by Iran could not, from all we know of Iranian decision-making, be undertaken simply on the president's say so but would also require the consent of the religious establishment; and that it is inconceivable that Iran's rulers would display such a complete disregard of Iran's true interests as to invite the retaliation against it that would surely follow.

The restraints governing the use of nuclear weapons rest on far more than the strong likelihood of retaliation. Any regime that used nuclear weapons in a first strike "bolt from the blue" would almost certainly be signing its death warrant. The infamy that would attach to any such action, both at home and abroad; the license it would give to others to retaliate or otherwise attempt to bring the regime down; the international isolation and withering contempt it would draw upon itself; the reputation for brigandage it would entail--all this constitutes an insurance policy against the dangers of an Iranian bomb. As a practical matter, it makes extremely unlikely--nay, virtually inconceivable--what is now taken by consensus opinion in America as a sort of moral certainty.

The Perils of Preventive War

Were the Iran crisis to follow the Iraq script, it is to be expected that the advocates of a preventive war would simultaneously maximize the dangers of not acting and minimize the dangers of so acting. That pattern would likely hold good in the event the United States approached the brink of war, but so far at least there is an acknowledgment, even among those who believe that preventive war must remain an option, that the consequences could be very serious indeed. Still, if the hypothetical costs of not acting are seen to be infinite, even the disastrous consequences of a preventive war may be seen as a case of faute de mieux.