Unthinkable (40 page)

Nevertheless, it seems more likely that Iran would fight back as best it could. The Iranians have threatened to hit pretty much everything in the region that the United States might value even a little: American bases, Israel, Turkey, Saudi Arabia, and any other country that provided assistance to the United States for the operation.
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Khamene'i has repeatedly threatened heavy responses to any American or Israeli attack, and so Tehran might feel compelled to retaliate or else lose any ability to deter subsequent attacks.
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The quickest and most direct response that Tehran could employ would be to lob ballistic missiles at U.S. bases, oil facilities, and other high-value targets located in the Gulf states, Israel, or other U.S. allies. Iran probably has several hundred ballistic missiles that could be used for this purpose, but they are inaccurate and unlikely to do much damage unless directed at cities. Nevertheless, this contingency could drive up oil prices and would still require the United States to deploy considerable antiballistic missile defense assets in the region and provide as much warning to U.S. allies as possible.

Because many Iranian leaders would look to emerge from the fighting in as advantageous a strategic position as possible, they might refrain from any direct retaliatory actions. As Kroenig explains, “Tehran would certainly feel like it needed to respond to a U.S. attack, in order to reestablish deterrence and save face domestically. But it would also likely seek to calibrate its actions to avoid starting a conflict that could lead to the destruction of its military or the regime itself.”
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Thus Iran might keep such missile attacks small and limited, and might refrain from targeting sensitive sites such as the Saudi oil fields, because any damage to them might provoke an even greater American response—and in that case, potentially with widespread international support.

Iran would almost certainly seek to convince Hizballah, Hamas, PIJ, or
its other proxies and allies in the Levant to attack Israel with rockets, missiles, mortars, and any other weaponry on hand.
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From Iran's perspective there would be little to lose and much to gain. Because Israel's ability to strike directly at Iran is limited (especially compared to the damage that the United States would have just inflicted on Iran), Tehran might have little to fear. Indeed, Israel's most likely and most powerful responses would be directed against the attackers themselves and the Iranians are probably more than willing to fight to the last Palestinian or Lebanese. However, by attacking Israel, Iran and its allies might be able to stir Arab and Muslim public opinion, possibly even painting the conflict as a new Arab-Israeli or Muslim-Israeli war. That may be a long shot, but given the limited downside for Tehran, why wouldn't they try? Indeed, most Israeli experts expect that they will.
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All that said, by far the most likely methods of Iranian retaliation would be covert: cyberwarfare and terrorist attack. Such responses could be immediate and coincident with a U.S. air campaign. Iran is believed to have extensive contingency plans for attacks on American targets, and it might be possible for Tehran to execute some terrorist operations in days and cyberattacks in hours. The U.S. intelligence community took the Arbabsiar case as proof that Iran is now willing to conduct terrorist attacks on American soil and believes that Iran is readying more such attacks to respond to an American military action.
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Iranian covert retaliation might also come well after the fact. If Tehran wanted to retaliate in spectacular fashion, especially on American soil, it might take longer to arrange. Major terrorist operations require extensive planning and preparatory work, and they have been especially difficult to execute in the United States ever since the security improvements that followed 9/11. Likewise, Iran might have to develop a more deliberate and complex cyberattack to get past U.S. defenses and cause significant harm to a significant American target or network. At a minimum, the United States would have to take steps to secure and harden U.S. targets against possible Iranian retaliation by cyber or terrorist attack and even then they might not prove fully effective.

Iranian terrorist and cyber attacks might also target America's allies, particularly those Iran might be looking for an excuse to attack anyway. Iran might try to stir up trouble against the governments of U.S. allies in the Gulf, especially Bahrain, Kuwait, and Saudi Arabia, all of whom have large Shi'i populations in which Iranian intelligence services have made significant inroads. Iran has attempted to overthrow all of these governments in the past, and they might be tempted to do so again.
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WOULD IRAN ATTACK THE STRAIT OF HORMUZ THIS TIME?
It is somewhat more likely that the Iranians would attempt to disrupt traffic in the Strait of Hormuz in response to an American air campaign than an Israeli operation. At an obvious level, the Iranians have threatened to close the Strait in response to an American attack and might feel the need to demonstrate that they meant what they said. In a 2012 crisis simulation we ran at Brookings's Saban Center, the Iran team saw restoring its deterrent as a compelling motive for Tehran and ordered limited mining and harassment of U.S. naval forces in the Strait. In the game, both of these actions got out of hand and provoked the United States to mount a massive military campaign to obliterate Iranian naval and air forces along the Strait of Hormuz littoral.
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Of course, the Iranians have also threatened to close the Strait if the West imposes new sanctions on Iran, and they have never made good on those threats, suggesting that the actual Iranian leadership may behave more cautiously than our Iran team in the simulation.
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Uncertainty is another factor that might push Tehran to move against the Strait of Hormuz. In most cases, if the United States decided to attack Iran's nuclear sites it would go for a bigger, longer campaign to ensure the maximum damage. In these scenarios, the United States would probably begin by building up its air, naval, and ground forces. This buildup, which might be fairly brief, would be followed by an initial wave of strikes against air defenses, key command and control facilities, and some leadership targets, to create a permissive environment for the strikes
against the nuclear facilities. This sequence of events is effectively identical to how the United States would mount either a decapitating air strike against the leadership or start a full-scale invasion. Thus the Iranians could not assume that a limited American buildup meant only limited American military objectives.

In addition, because Iran's command and control network is old and imperfect, Tehran might be too confused by the initial American attacks to glean precise information about Washington's intentions. The Iranian leadership may only know that the United States is flying lots of strike sorties against it and is destroying a wide variety of important targets. In either of these circumstances, the regime might decide that it cannot afford to be wrong if it is a U.S. invasion, and might order a defensive closing of the Strait to try to prevent it.

Nevertheless, closing the Strait would hardly be an automatic response for Tehran. Iran's nuclear program is not the regime's highest priority, even if it is high on that list. They value their lives and their control of Iran even more. They also care a great deal about their oil production and export facilities, since those are the lifeblood of the Iranian economy and their own personal wealth. There is also their conventional military power, particularly their ability to threaten the Strait of Hormuz, which effectively constitutes their only economic and strategic leverage over other countries. All of these assets would also be vulnerable to American attack. The Iranians would hopefully recognize that they have even more to lose if they provoke the United States to escalate further, particularly by threatening the world's oil lifeline through the Strait of Hormuz—as long as they can recognize that the United States is discriminating among these target sets.
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Moreover, as discussed in the previous chapter, while Iran might be able to close the Strait for a limited period, American air and naval assets should be able to reopen it in a matter of weeks or months.
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In so doing, the United States would probably cause enormous damage to Iran's air-, sea-, and ground-based military assets in the area. Iran has spent huge
sums to build up these forces over the past two decades, and they are far too valuable to Iran as latent threats with which to manipulate the oil market to risk losing them by closing the strait.

If the Iranians did move against the Strait and closed it for some period of time, the damage they could do to the global economy could be significant albeit short-lived. At present, about 17 million barrels per day (bpd) flow through the Strait of Hormuz, amounting to 35 percent of global seaborne traded oil.
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If that oil cannot be exported through the Strait, there is no way to replace it by producing more elsewhere, as virtually all of the world's spare oil production capacity is located in the Gulf countries.
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About 2.5 million bpd could be rerouted through pipelines across Saudi Arabia and the UAE, but the 14.5 million bpd that would still be trapped by the closure of the Strait amounts to more than 16 percent of global oil consumption.
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In theory, the strategic oil reserves of developed nations could make up for the loss of 14.5 million barrels per day, and could do so for about one hundred days.
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(There are also private stocks of oil held by companies, but these fluctuate markedly. Thus, while they would certainly help, and potentially a lot, it is hard to calculate by how much.) Nevertheless, if strategic reserves cannot be released with efficiency and speed (and releases have typically proven slower than projected), the price of oil could rise significantly. Likewise, if the Strait were closed for more than three to five months, prices would rise as well. Meanwhile, eleven of twelve major American postwar recessions were preceded by a jump in oil prices.
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Many people believe that it would be possible for the United States to mount limited air strikes against the Iranian nuclear program without having to commit to a wider war, or an invasion of Iran. This is one of the most important arguments in favor of air strikes. While I think this is possible, I think it much less likely than its proponents believe. I see a considerable risk, even a likelihood, that it would not be possible to do so.

There are several dynamics at work that make it fairly likely that air strikes against the Iranian nuclear program would be the start of a much larger U.S.-Iranian war,
one that could well push us into an invasion of Iran
. That is a big statement. It means that what seems like a major undertaking by the United States itself—several hundred or several thousand air and missile sorties against Iranian nuclear and air defense sites over the course of days or weeks—could morph into a truly massive American ground invasion of Iran requiring several hundred thousand ground troops occupying the country for years or even decades. Yet wars are always inherently unpredictable and often turn out much worse than their authors intended, especially when the instigators do not prepare for it to go badly.

First, there is the likelihood of Iranian retaliation. We don't know what the Iranians will do, how effective their retaliation will be, or how effective our defenses will prove. The available evidence indicates that they will retaliate, they will want to inflict significant pain, and that they have a reasonable capability to do so—primarily by terrorist and cyberattack. If Iran is able to hit us or our allies hard, there will be significant pressure on the United States to respond, especially if Iran is not content with a few retaliatory shots but continues to wage asymmetric campaigns (terrorism, cyberwarfare, periodic missile and rocket attacks) for weeks, months, even years—all of which it is capable of doing and has threatened to do. Moreover, if any such attacks were to cause major loss of life, or if the Iranians make any move to threaten the Strait of Hormuz, there would be tremendous pressure on the U.S. government to respond with overwhelming force to reopen the Strait, deny Iran the capacity to further threaten the United States or our allies, and convince Tehran to stop attacking us.

Depending on the extent and length of this retaliatory damage, there is a real risk of an escalatory spiral between the two sides that would lead to a much wider war. War games of small-scale crises between Iran and the United States have repeatedly demonstrated how easy escalation is between the two countries, given the hard feelings, deep suspicions, constant misinterpretations, and painful history between them. Similar
studies and simulations of a conflict with Iran have also pointed to the difficulty of bringing such a war to an end short of an invasion—something reinforced by America's difficulties convincing Iran to desist during the “Tanker War” of the 1980s.
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Second, any American president who commits the United States to war with Iran, even if it starts out with discrete air strikes, will have a difficult time halting operations short of Iran's full capitulation (at least on the nuclear issue), regardless of the success or failure of that air campaign. If the president goes before the nation and explains that the threat of a nuclear Iran to American interests is so grave as to warrant the United States going to war with Iran (unprovoked) by launching hundreds or thousands of air sorties against dozens of Iranian targets, possibly resulting in hundreds or even thousands of deaths, he or she is not going to be in a position to announce a few weeks later that the strikes failed and Americans will just have to learn to live with a nuclear Iran. Nor is the president going to be able to accept a defiant Iran announcing after successful air strikes that it will rebuild its nuclear program and this time will not stop with enrichment but will continue on to field an arsenal. In either circumstance, if the threat were that grave to begin with—grave enough to court retaliation that could result in further American casualties—the American people would demand that we commit more of our fearsome military power to finish the job.