Unthinkable (41 page)

It is conceivable that the air strikes will do the job on their own and will either bring about a regime change or convince the Iranians not to begin rebuilding their nuclear program. It is also possible that Iran will retaliate in a modest fashion so as not to provoke a larger American response, or that Iranian retaliation will be defeated by American countermeasures and whatever pain we suffer will be modest enough to ignore or to respond to with equally limited measures.

However, these more optimistic scenarios appear to be the less likely outcomes. Although the United States is in a far stronger position than Israel would be on either of these scores, it appears more likely that the Iranian regime will not be overthrown and that whatever damage the air
strikes may do, it seems probable that the regime will choose to reconstitute rather than give up. Likewise, the Iranians will almost certainly try hard to inflict considerable damage on the United States and will have a good chance of doing so.

No American president could order air strikes without recognizing the likelihood that doing so will end up committing the United States to a wider war with Iran and possibly a ground invasion. More to the point,
it would be irresponsible for a president to order air strikes against Iran without having accepted that doing so may mean committing the United States to an eventual invasion
.

As we should have learned from our painful experiences in Afghanistan, Iraq, and the Balkans, when the United States starts down the path of military action it is extremely difficult for our nation not to walk that road to its very end, whatever that end may be. In all of those cases, the United States tried limited military operations at first, only to find itself forced to commit to larger operations and eventually a major invasion and occupation. In the case of the Balkans, Milosevic's concessions on Kosovo in 1999 ultimately obviated the need for ground invasions and limited the extent of the postwar commitment. However, the United States was reluctantly gearing up for a ground invasion just when Milosevic's capitulations relieved us of the need to actually execute it. The same might happen in Iran, but no responsible president could start down the path of military action assuming it will. And unfortunately, the pathologies of the Iranian regime create the very real likelihood that it will require a much greater military effort, even an invasion and occupation of the country, either to prevent it from reconstituting its nuclear program or to force it to halt its retaliatory attacks against the United States.

It is easy for those who do not sit in the Oval Office to dismiss the prospects of a wider war with Iran or the need for an invasion and occupation of the country growing from “limited” air strikes against Iran's nuclear program. The person who sits there cannot. He must think through what his decision will entail, what it may commit the United
States to accomplish. It would be reckless and irresponsible for him to assume that air strikes would
not
lead us into a situation requiring a greater military effort.

Since air strikes against Iran raise the specter of an invasion, unwanted though this would be for virtually every American, it is important to sketch out the basics of such an operation.

MILITARY ASPECTS OF AN INVASION.
⁹⁶
As with Iraq and Afghanistan, the military requirements for an invasion of Iran could prove deceptive. The invasion itself would be a major military operation, but one well within the capability of American forces. Although Iran's armed forces are roughly twice as large as Saddam's were in 2003 (750,000 to 1 million in the Iranian Armed Forces today, compared to about 400,000–500,000 in Iraq's various military services then) and probably would perform somewhat better than the Iraqis, they are outclassed by the American military. Once in, however, a long-term commitment would be necessary, greatly increasing the likely requirements.

A U.S. invasion force would face two primary military obstacles against Iran: terrain and insurgents. The first of Napoleon's “Military Maxims” was “The frontiers of states are either large rivers, or chains of mountains, or deserts. Of all these obstacles to the march of an army, the most difficult to overcome is the desert; mountains come next, and broad rivers occupy the third place.” Iran has few broad rivers, but many mountains and deserts, the hardest types of military terrain. Iran has considerable experience with guerrilla warfare through its long association with Hizballah and the support it provided for the latter's guerrilla wars against Israel in southern Lebanon. After watching the American blitzkrieg to Baghdad in 2003, the Iranians have concluded that the best way to fight the U.S. military would be through a protracted guerrilla war, bleeding American forces as they wend their way through the arduous
mountain chains that fence in the Iranian heartland and wearing them down in what Tehran has dubbed a “mosaic defense.”
⁹⁷

To deal with the terrain and Iran's defensive strategy, an American invasion of Iran would require a variety of forces. First, it would probably involve a significant contingent of Marines (two to four regimental combat teams, or about 15,000–30,000 Marines) to seize a beachhead and then a major port at one of four or five general locations where such a landing could be staged along the Iranian coastline. To get past the mountains, the United States would want large numbers of air mobile forces—the brigades of the 101st Air Assault Division and the 82nd Airborne Division, and possibly the 173rd Airborne Brigade as well. Beyond that, the United States would want at least one, and as many as three, heavy armored divisions for the drive on Tehran itself (depending on the extent to which the Marines and air mobile units are tied down holding the landing area and mountain passes open, as well as providing route security for the massive logistical effort that will be needed to supply the American expedition). A force of four to six divisions amounting to 200,000–250,000 troops may lead the charge, larger than that employed at any time during Operation Iraqi Freedom and much larger than the 55,000 ground troops that took down Saddam's regime in the initial invasion.

Although Washington might secure bases in the Gulf states (and perhaps in some Central Asian countries as well), it seems unlikely that Iraq, Turkey, Pakistan, or Afghanistan would allow us to mount the invasion from their territory. Consequently, an invasion would require a large naval contingent to secure the Persian Gulf and carry the invasion force to the shores of Iran. It is thus unlikely that the United States could launch such an enormous military operation without the Iranian government getting a sense of what was headed its way.

In these circumstances, where the regime's survival would be at stake, the Iranians would have no incentive to show restraint in fighting back any way they could: with terrorist attacks anywhere they could hurt Americans, with rocket and missile attacks across the Persian Gulf, and
by trying to close the Strait of Hormuz. Iran has some dangerous air, sea, and missile capabilities, but, as noted earlier, if the U.S. Navy and Air Force brought their full might to bear, they could crush Iran's air and sea defenses in a matter of weeks or months. This effort, however, would require a major commitment of American minesweeping, surface warfare, and air assets. It also would require a cutoff of Persian Gulf oil flows for at least as long as the Iranians contested the waters of the Gulf and the Strait.

As with an air campaign against Iran, the U.S. Air Force and Navy probably could handle the airpower requirements without the use of Saudi, Kuwaiti, Qatari, Emirati, Omani, Turkish, or Central Asian air bases, but it would be much easier with them. Long-range bombers could fly from the continental United States or Diego Garcia (with British permission), but unless the Gulf or Central Asian countries could be persuaded to allow the U.S. Air Force to operate from nearby airfields, the vast majority of American aircraft would have to operate from aircraft carriers. Given the extent to which modern U.S. ground operations rely on air support, three or more carriers might be needed for this campaign, at least until Iranian air bases could be secured and developed to handle U.S. Air Force planes.

Similarly, if the United States were denied access to its many bases in the Persian Gulf region, the Navy would have to bring in everything needed to support the invasion, and U.S. engineers would have to build facilities at Iranian ports to enable them to support a massive force. Indeed, because the expanses of Iran would be much greater than in Iraq (distances from major Iranian ports to Tehran are anywhere from one and a half to three times as great as those from the Kuwaiti border to Baghdad), and because of the much more difficult terrain, the logistical requirements for an invasion of Iran could be considerably more demanding than those for Iraq.

THE OCCUPATION.
So much for the takedown. Now to the hard part. In both Iraq and Afghanistan, the United States tried to get rid of the regime
and then go home, leaving the country in the hands of a hastily cobbled-together successor government of exiles. In both cases, the effort failed, and the country began to descend into chaos. In both places the Bush 43 administration was forced, against its will, to embark on a long-term occupation and reconstruction of the country.

It is unimaginable that the United States would not find the exact same thing in Iran. Iran is an even bigger oil producer than Iraq. It too occupies a central position in this vital region. Its influence and relationships throughout southwest Asia make it a key actor. If it fell into civil war and chaos, the spillover would infect the entire region. And the occupation of Iran would be a major undertaking.

This will likely prove true even if Washington has learned all the lessons of Iraq and mounts the invasion and occupation of Iran exactly as it should have in Iraq. Iran is a much bigger country than Iraq, with nearly three times the population and roughly four times the landmass. It too has myriad ethno-sectarian divisions and grievances, and a traumatic history of sanctions and authoritarian misrule. Thus the challenges of occupying and building a stable new Iran are likely to be nearly identical to those of Iraq, just bigger.

All low-intensity conflict operations, whether a counterinsurgency campaign or a stability operation like securing post-invasion Iran, require large numbers of security forces, because the sine qua non of success is securing the civilian populace against widespread violence. Scholars and low-intensity conflict experts have found that it takes about 20 security personnel per 1,000 people to secure civilians against insurgencies, militias, and other forms of violence common in postconflict reconstruction.
⁹⁸
This ratio suggests that an occupation force of 1.4 million troops would be needed for Iran. That ratio is basically the same that succeeded in stabilizing Iraq in the 2007–2008 “surge” (taking into account American troops, security contractors, allied contingents, and the enlarged and improved Iraqi Security Forces).
⁹⁹

There is reason to believe that high-quality troops with lavish support assets (like the U.S. military) can get away with less than the canonical
figure. But even if the United States, by relying on far superior training, technology, and tactics, could cut that number in half, the remainder still represents the
entire
active-duty component of the U.S. Army and Marine Corps. Even if it were only necessary to maintain such a large force for the first six months, after which the United States could begin drawing down its forces quickly (as experience in the Balkans and even Iraq suggests is possible), such a commitment would still require a massive mobilization of the National Guard and both the Army and Marine Reserves.

Again, assuming a best-case scenario in which the proper application of the lessons learned from Iraq and Afghanistan enables the invasion and occupation of Iran to go more easily, it would still take years to establish a stable, legitimate government with competent, loyal security forces. During that time, the United States would doubtless have to maintain several hundred thousand troops in Iran, even under ideal circumstances of full Iranian cooperation and minimal resistance.

THE COSTS OF AN INVASION.
Of course, it would be unwise to assume the best case. The Bush 43 administration's insistence that only the best case was possible in Iraq lies at the root of the concatenation of mistakes that produced the worst case there from 2003 to 2006. Iranians are nationalistic, and while many would welcome the end of the current regime and a better relationship with the United States, the evidence suggests that most would oppose a U.S. invasion. Indeed, the fact that the regime is preparing to wage a guerrilla war against the United States if it invades means we could have a long, hard slog ahead of us there.
¹⁰⁰

The United States lost nearly 4,500 troops securing Iraq, and more than 2,000 in Afghanistan as of early 2013, although it did not have any killed during the earlier occupation of Bosnia. It is impossible to know how many troops we might lose in a similar operation in Iran, but we should not assume it will be as easy as Bosnia, and it could be as costly as Afghanistan or Iraq, or worse. Hundreds or possibly thousands of
American military personnel would die in the invasion itself. Thereafter, casualty levels would depend on both the extent of Iranian resistance and the competence of the American security effort. The remarkable success of American forces in Iraq after 2007 demonstrated that the right numbers of troops employing the right tactics in pursuit of the right strategy can secure a country at much lower cost in blood than inadequate numbers of troops improperly employed. Prior to the surge—and during its heated early months when U.S. troops were fighting to regain control of Iraq's streets—American military deaths were running at seventy to eighty per month. Once that fight had been won, they fell to five to fifteen per month. U.S. casualties during the occupation and reconstruction of Iran could thus vary considerably. Only in the best-case scenario—where the securing of Iran is as smooth as NATO's securing of Bosnia—should policymakers expect minimal casualties. In more plausible but still favorable scenarios, where Iranian resistance approximates Iraqi levels of violence after the surge, the United States should still expect a dozen soldiers and Marines killed each month, on average, for several years. In worst-case scenarios, in which the United States mishandles operations in Iran as badly as it did initially in Iraq, those numbers could run into the hundreds each month, or worse.