At the top of U.S. Secretary of Defense Ashton Carter’s agenda for 2015 is stopping the Islamic State of Iraq and al-Sham (ISIS). Many critics assert that the current policy of limited air strikes is insufficient to defeat or seriously weaken ISIS and have offered radical alternatives. However, these “cures” are far worse than the disease. The best plan is to aggressively move forward within the broad parameters of the current strategy, building on its successes and vastly diminishing ISIS’ power and influence by the time U.S. President Barack Obama leaves office in two years.

GREAT EXPECTATIONS

There are two prominent (and nearly polar opposite) alternatives to current policy. At one extreme, CFR Senior Fellow Max Boot calls for the deployment of up to 30,000 U.S. ground combat troops, a U.S.-enforced no-fly zone, and incentives to enlist Turkey as an active military partner in the fight—all in order to push the Kurds, the Shia-dominated Iraqi security forces, and Sunnis to work together to roll back ISIS from its strongholds in Iraq and Syria. At the other extreme, retired Air Force Lieutenant General David Deptula argues that a vastly expanded air campaign against ISIS’ leadership and economic and military centers of gravity can so weaken the group that a broad Sunni resistance will quickly rise up, making any U.S. Special Forces on the ground unnecessary.

These proposals are as unrealistic as they are ambitious. No doubt, Washington would love to find a silver bullet to quickly defeat ISIS in Syria and Iraq, but neither of the proposals is likely to work as advertised. There are over 20 million Sunnis in Syria and Iraq, a large fraction of which are now cooperating (passively or actively) with ISIS and would fight hard to avoid Kurdish and Shia domination, much less American control. Meanwhile, sending in U.S. ground forces might help win bits of territory along the current perimeter of ISIS-held territory, but it is unlikely to weaken the group in the heart of the Sunni-majority areas. Even worse, marshalling a coalition of multiple enemies of the Sunnis could well deepen the local Sunni population’s cooperation with ISIS. The air-only option has the opposite flaw. It would possibly hurt ISIS in Raqqah and other parts of the Sunni heartland, but with little means to stop ISIS from responding by expanding its area of control elsewhere.

The alternative strategies promise too much. They are vulnerable to failure and risk overcommitment of U.S. forces without reasonable prospects of major strategic benefits. Worse, if any of the proposals’ intermediate steps fail to come to fruition, the United States will be left holding the bag, with no option other than committing more and more ground troops to a messier and messier conflict in Syria and Iraq.

FIGHT SMART

A plan to reclaim territory currently held by ISIS in Iraq that has more limited short-term objectives would be less vulnerable to failure. There is a fundamental strategic asymmetry between the situations in Syria and Iraq. In the short term—the next two years—Syria is likely to remain intractable. Whatever local ally works with the United States must fight a two-front war, confronting Syrian leader Bashar al-Assad and ISIS simultaneously—a task so daunting that it is hardly surprising that the Free Syrian Army has failed at it. In Iraq, by contrast, there are real possibilities for success. Indeed, success in Iraq can serve as a basis for achieving significantly more in Syria in the future.

Since early August, when the air campaign began, there have been over 1,200 U.S. air strikes against a variety of targets carried out by all manner of manned aircraft and drones. How do we know if the air campaign has been effective? Analysts and the administration have made conflicting claims. Here, more precision about the meaning of effectiveness is warranted.

There are two bases for assessing the effectiveness of air campaigns. The first is tactical: Have strikes succeeded in destroying ISIS fighters and materiel? The second is strategic: Have they contributed to thwarting ISIS’ goals in the region?

Few disagree that air strikes have been effective at the tactical level. Coalition planes have destroyed countless ISIS vehicles, eliminated ISIS cadre, and disrupted oil-producing infrastructure. All the while, there have been no casualties on the Coalition side.

The lingering question, however, is whether tactical successes have amounted to a strategic one. It is at the level of strategic success that there has been the most ambiguity and confusion. Some critics argue that air power has failed to incapacitate and destroy ISIS, which is evidence, they say, that the United States needs a new strategy. However, the rapid elimination of ISIS is not a realistic objective for airpower, or any military campaign for that matter.

A more reasonable standard is whether airpower has been able to blunt ISIS’ ability to take and hold territory. After all, ISIS has two overriding goals: expansion and consolidation of control. By this measure, the air campaign has achieved important success in blunting ISIS’ offensive strategy of expanding its perimeter but has failed to counter ISIS’ defensive strategy of consolidating Sunni-majority areas.

TACTICAL TRIUMPH

Pape, Ruby, Bauer

In June and July, ISIS achieved stunning victories when it overran important Sunni-majority areas, particularly Mosul, Iraq’s second largest city. At this point, ISIS threatened to rapidly expand its areas of control into the Kurdish areas of northeastern Iraq and into the Shia areas in and around Baghdad as it moved toward Irbil, the Mosul Dam, Sinjar, and south of Baghdad. Given the recent loss of Mosul and the collapse of the Iraqi Security Forces in that city, there was reason to worry that, without international intervention, ISIS would win more territory.

The U.S. air campaign began in August and quickly halted ISIS’ expansion beyond the Sunni majority areas. Air power was a valuable tool in limiting ISIS’ potential expansion for three reasons. First, it could flexibly shift to the defense of various areas, depending on the degree of effort ISIS chose to exert against them. Second, U.S. airpower is especially effective at destroying clustered and massed enemy military units, and so limited the quantity of forces that ISIS could bring to bear in any one battle. Third, U.S. airpower could work in close conjunction with local ground forces, both bolstering their morale and serving as a force multiplier in specific ground encounters.

Put differently, the U.S. air campaign succeeded in blunting ISIS’ drive toward Kurdish and Shia territory by using a strategy called “hammer and anvil.” The strategy put ISIS in a catch-22: It could either choose to concentrate its forces to achieve local superiority over opposing ground troops and then be decimated by the United States’ airpower “hammer”; or it could avoid airstrikes by dispersing its forces into small units and so be vulnerable to defeat by the opposing ground force “anvil.” Either way, ISIS loses.

STRATEGIC STALEMATE

Pape, Ruby, Bauer

The current air campaign has failed, however, to prevent ISIS’ consolidation of control over the Sunni areas in Iraq and Syria. Since mid-summer, ISIS has made territorial gains, most notably in Hit, Ramadi, Raqqah, and other areas deep inside the Sunni heartland. In response, there have been airstrikes against ISIS’ command-and-control structures and its revenue generating oil operations, strikes limited mainly by available intelligence. However, these strikes against leadership and economic targets have made little difference, and hitting them again would not change the situation.

Airstrikes against ISIS leaders and the group’s economic base are unlikely to seriously weaken the group. To be sure, these “decapitation” tactics may, over time, kill leaders and destroy economically valuable assets—losses that could disrupt the group’s operations. However, without additional measures to exploit this disruption when it occurs, the group can simply select new leaders and generate more resources, making the overall strategic impact of decapitation minimal. Since 2006, the United States has killed the past three leaders of ISIS and its forerunners, and each time, a new leader emerged with little trouble.

A new hammer-and-anvil approach—air power in combination with local ground forces—does offer a reasonable approach to rolling back ISIS control of Sunni areas, but current ideas that emphasize Kurdish or Shia-led Iraqi Security Forces would likely fail, if not make matters worse. As in Mosul and numerous other areas where ISIS has easily taken control, the Kurds and Shia are not willing to pay the costs to hold or retake Sunni-majority areas. Even if the United States could somehow coerce or cajole them into taking offensive action, that would likely to do more to further mobilize the 20 million Sunnis in the area to fight for ISIS. It would also take the option of a mutually acceptable settlement between Sunni and Shia leaders off the table. After all, ISIS is capitalizing on a widespread Sunni revolt in both Syria and Iraq to being governed (unfairly, as Sunni see it) by Shia-dominated governments in both places. Encouraging a return to greater Shia control is only going to deepen Sunni fears, strengthening rather than weakening ISIS.

HOW TO WIN

Defeating ISIS requires a new strategy for retaking Sunni territory. The strategy should incrementally build on the current hammer-and-anvil approach that has successfully blunted ISIS’ expansion into Kurdish and Shia areas. The conditions are ripest for a Sunni anvil in Nineveh and Anbar provinces in Iraq, so these areas should be the focus of a new plan with four components.

The first objective should be to maintain the gains that the United States has already made. Accordingly, the United States should continue using airstrikes in Iraq and Syria to prevent ISIS from expanding territory under its control, especially at the expense of local allies. The air campaign has proved successful in halting ISIS’ advances toward the Kurdish capital of Erbil and the Shia areas around Baghdad. The United States should deploy Special Forces and combat air controllers to support local allies, but only a very small number (fewer than 100) and only at the perimeter to minimize the risk of U.S. soldiers falling into ISIS’ hands.

Second, the United States should secure a power-sharing agreement between the Iraqi government and Sunni tribes that allows greater autonomy for Sunni provinces—like that granted to the Iraqi Kurds. Oppression of the Sunnis by the Shia-dominated Iraqi government was a core reason mobilizing Sunni support for ISIS in the first place. Eliminating Sunni fears that a post-ISIS Iraq would simply replace domination by ISIS with a return to Shia domination will be key. In addition to political autonomy, Sunni control over the local police and security forces would be an important component of such a deal.

Third, the United States should expand the use of air power to limit ISIS’ ability to move large forces freely between Syria and Iraq. Air power cannot completely seal the border: ISIS will still be able to move some forces across it. However, as the current air campaign has demonstrated, such tactics are highly effective against concentrated forces, and can stop ISIS from moving men and materiel in large concentrations, which significantly limits ISIS’ ability to reinforce positions in Iraq (just as pressure on those positions mounts). This will provide a credible security guarantee to Iraqi Sunnis that ISIS’ power over them is limited.

Fourth, it will be necessary to roll back ISIS in key Sunni areas. Together, the first three steps will weaken ISIS’ control in Iraq. Guaranteeing Sunni political and security autonomy while containing ISIS expansion and mobility will make Sunnis more likely to resist ISIS. Meanwhile, strengthening local allies with minimal U.S. presence will not only improve the effectiveness of the air campaign but also empower the only force with a real incentive to roll back and defeat ISIS in combat. The strategy would strongly emulate the 2001 Afghan campaign, where local allies together with only 50 U.S. Special Forces managed to defeat the militarily superior and entrenched Afghan Taliban.

The crucial next step is to identify pockets of Sunni resistance to ISIS and support them. There are two obvious places to start. One is the Nineveh province police force, which numbered roughly 24,000 when ISIS took control of much of the province in June but was instantly cut off from all funds and weapons by the distrustful Shia-dominated government in Baghdad. The other is the Sunni tribes that have opposed ISIS in Anbar, such as the Jaghaifi, near Haditha, and Albu Nimr, near Hit, hundreds of whom were brutally killed by ISIS in an effort to suppress their opposition during the recent conquest. If supported by U.S. airpower and Special Forces, both groups have the self-interest and potential numbers to create the beginnings of a serious ground challenge to ISIS controlled territory in Anbar. Given that 1,500 U.S. Special Forces typically expect to train 15,000 local forces per year, even the current contingent of 3,000 advisers can expect significant results if focused on supporting a Sunni-based opposition force.

To maximize the prospects of successfully rolling back ISIS from Sunni areas in Iraq, the United States should resist getting drawn more deeply into Syria. For the next two years, the best way to weaken ISIS in Syria is indirectly. Specifically, reversing ISIS’ momentum in Iraq will also likely weaken the group in Syria at least compared to other Sunni groups, changing its trajectory from a rising dominant force to one of numerous fragmented factions. As a result, pursuing this pragmatic plan is not only the best way to achieve real success against ISIS in Iraq; it is also the best approach to make Syria more manageable for the next administration.

The pragmatic plan to defeat ISIS is hardly perfect. It separates Syria from Iraq and so pushes off numerous important questions (such as Assad’s political future and the fate of Raqqah, ISIS’ putative capital). It requires brokering robust political and security autonomy for Sunnis that the Shia-dominated government in Baghdad would be loath to accept. However, by marshalling the United States’ considerable strategic assets with local allies with a genuine interest in opposing ISIS control of territory, this plan has realistic prospects for meaningful and sustained success over the next two years.