In his recent essay for The Atlantic, David Ignatius has, with characteristic elegance and care, detailed “how ISIS spread in the Middle East.” In addition to providing an instructive history of a metastasizing malignancy, he offered some ideas on how to prompt its remission.

This response seeks to pick up where Ignatius left off, with emphasis on Syria. The argument here is, first, that civilian protection in western Syriawhere the regime of Syrian dictator Bashar al-Assad fights for survival—is the mandatory first step toward the negotiated political transition Ignatius deems essential for uprooting ISIS, given how Assad has enabled the group. Second, an American-led coalition, consisting largely of regional and European ground forces, will be required to sweep ISIS from its main Syrian bases in the east. Military victory in Syria, the soft underbelly of ISIS, will leave the group isolated in Iraq— without its Syrian headquarters, oil resources, and lines of communication—thereby turning the tide of battle against ISIS in that country as well. It is Syria, where ISIS is largely imposed rather than homegrown as it is in Iraq, that should be the top battlefield priority.

Ignatius documents how ISIS filled vacuums of political legitimacy in both Iraq and Syria. Nouri al-Maliki’s corrupt sectarianism led many Sunni Arabs in Iraq to conclude that he had no right to serve as the country’s leader, and that both he and the system that produced him were illegitimate. In Syria, the clan-based Assad regime has produced parallel results: The spread of protests against Assad’s corrupt and arbitrary rule in 2011 showed that his regime had lost legitimacy for much of the population four years ago. Judging solely by the numbers of refugees and internally displaced people Syria has generated since then—in no small part due to Assad’s political-survival strategy, which features the mass homicide of civilians—this sentiment has dramatically intensified.

In Iraq, Maliki was belatedly hustled offstageperhaps too late. But in Syria, Assad persists, largely due to Iranian and Russian support. It should be clear to leaders in Moscow and Tehran that Assad’s agenda of collective punishment pumps oxygen into the lungs of the ISIS “caliph,” Abu Bakr al-Baghdadi, whose movement attracts recruits from around the world in part because of Assad’s brutality. The Iranians and Russians don’t care. Both governments, for separate reasons, want Assad to survive politically in at least part of Syria. Each sees ISIS as its client’s return ticket to polite society. Each strives to create a purely binary choice for the West: Assad or Baghdadi? Each counts on the West to conclude, once all other alternatives to Assad are killed off, that the barrel bomber is less bad than Baghdadi.

As much as Barack Obama wants to avoid direct military action against Assad, the U.S. president has stated a desire to “degrade and destroy” ISIS. Indeed, ISIS can—given a major American-led strategic shift—eventually be militarily defeated in Iraq and Syria and forced to disperse or go underground. It will not, however, be destroyed per se until the vacuum of legitimate governance is filled in both places. Iraq’s new prime minister, burdened by the “assistance” of a relentlessly sectarian Iran, is at least trying. Assad seems to believe, however, that Syria is his patrimony and that he personally embodies legitimacy, regardless of what Syrians may think.

In Syria, American policy currently features the hope for an Assad-free diplomatic outcome in the west paired with a desultory air campaign against ISIS in the east. Notwithstanding the skills of coalition pilots and the irrepressible energy of U.S. Secretary of State John Kerry, the chances are good that Obama will bequeath to his successor a Syria all but partitioned between two criminal elements (Assad and ISIS)a country hemorrhaging humanity in all directions while international terrorists feast on the carcass of what was once a unitary republic. The four-plus years the United States spent holding Syria at arm’s length, hoping its carnage could be contained while drawing erasable red lines and merely calling on Assad to step aside, have helped to spawn horrific unanticipated consequences and narrowed policy options. Decisions America deferred in 2012 came home to roost in 2015. Everything is harder now, and policy choices run along a spectrum of bad to worse, with “inaction” firmly situated at the “worse” end. And yet hard decisions, if avoided in 2015, can haunt Obama’s successors for decades to come. What should be done right now to defeat ISIS?

In western Syria, the United States and its partners should make civilian protection the near-term centerpiece of their anti-ISIS strategy, before even beginning to seek the political solution Ignatius rightly calls the best hope for Syria’s survival. The objective should be twofold: terminate the ability of the Assad regime to kill large numbers of civilians, whether with barrel bombs, artillery shelling, high-performance aircraft bombing and strafing, or missile attacks; and oblige the regime to lift sieges that deny food and medical care to up to 600,000 Syrians. Blunting Assad’s policy of collective punishment ought to be a humanitarian imperative. But it will be good enough if the Obama administration sees civilian protection as an essential anti-ISIS war measure, which it most assuredly is.

How to do it? First, lean hard diplomatically on Russia and Iran. The recent meeting in Vienna among diplomats from world and regional powers means nothing and goes nowhere unless Syrian civilians receive protection from the depredations of their own so-called government. Leaders in Tehran and Moscow have it in their power to compel their client to stop bombing civilians and to lift starvation and disease sieges in accordance with UN Security Council Resolution 2139. After all, without Russia and Iran, Assad is finished. The United States should present them with a straightforward proposition: Get your client to stop committing war crimes and crimes against humanity, or we will take steps to protect Syrians. Russia’s UN ambassador, Vitaly Churkin, announced the day after the Vienna meeting that the Assad regime had stopped barrel bombinga positive development if true, and an interesting one given Assad’s repeated denials of having used those weapons at all.

If Churkin’s report proves inaccurate, and if Russia and Iran fall short of stopping Assad’s crimes, the United States must take military action to protect civilians, striking the systems and facilities involved in operations of mass homicide: helicopter bases where barrel bombs are loaded, artillery formations, missile facilities, and air bases. “Zones” of the kind Ignatius advocatesno-bombing, no-fly, protected, etc.need not be declared or maintained in western Syria if the initial objective is to stop mass-casualty events by targeting offending regime assets. Focused in this way, such actions need not engage Russia militarily.

In eastern Syria, where the threat to Syrian civilians now comes mainly from ISIS and not the Assad regime, it is the absence of capable ground combat forces that cripples the anti-ISIS military campaign. An air campaign alone cannot produce decisive results. Kurdish militiamen are too few and too focused on creating and maintaining a contiguous ethnic zone of their own in northern Syria. Organizing bands of eastern Syrian Arabs to fight ISIS is, at best, a work in slow progress. The 50 American Special Operations Forces the Obama administration will be deploying to northeastern Syria can do some good, but without real ground power, military victory over ISIS in Syria will be elusive and too long in coming.

The remedy is obvious but very hard to achieve: an ambitious American diplomatic effort to bind regional and European powers to commit ground forces to rout ISIS from Syria. At present, there is not a single Middle Eastern state—not Turkey, not Jordan, not Egypt, not any of the Gulf states—interested in committing troops to Syria. The same is true of France, Great Britain, and others. Are they persuadable? The United States cannot know without trying to persuade. A quarter-century ago, U.S. Secretary of State James Baker could have easily convinced himself that trying to build a coalition to liberate Kuwait would be too hard and a monumental waste of time.

The analogy is, to be sure, inexact. In 1991, conventional American ground forces accounted for the overwhelming preponderance of coalition combat capability directed against Saddam Hussein in Iraq. If an anti-ISIS coalition were formed now, 25 years later, American boots would likely be on the feet of Special Operations Forces—albeit far more than 50—who would make life absolutely miserable and brief for the ISIS rabble. Regional forces, in this case, would provide the requisite infantry, artillery, and armor units, supplemented by European combat-support elements. In 1991, Baker did not have to expend much effort convincing allies and partners that America was committed for the duration of the military campaign and would not abandon anyone signing on to the coalition. For the Obama administration, that case will be exponentially harder to make. But making it is essential.

Sweeping ISIS from eastern Syria would create the mother of all protected zones: The roughly half of Syria estimated to be occupied by the “caliph” and his minions. It would terminate Russia’s pretext for military intervention in Syria and preempt the trapping of the West in a binary Assad-Baghdadi choice. Combined with civilian protection in western Syria, it would establish a solid foundation for all-Syrian dialogue, negotiations, political transition, and ultimately elections.

For the Obama administration, the temptation to say, “It’s too hard to do and we can’t do it anyway” may be overwhelming. As Ignatius notes, this is a bunch that took perverse pleasure in the failure of its own train-and-equip scheme. On the other hand, however, Obama is not unaware of the problems with his “degrade and destroy” objective. As the leader of a great alliance, he knows the unreasonable burdens being placed on America’s European allies by the progressive emptying of Syria. Surely the slaughter of Syrian civilians and the lack of ground-combat capability against ISIS in Syria bother and frustrate him.

The anti-ISIS “long game” centers on clearing a path for legitimate governance, reflecting the voluntary consent of the governed, in both Iraq and Syria. Whether or not a legitimate system can be devised to cover all of Iraq is a real question, and it may be premature at this point to talk about “solving Syria.”  

Yet one thing is certain, at least about Syria: The country’s destructive, destabilizing dismemberment cannot be contained—much less solved—with civilians in Assad’s bullseye and ISIS in business. The beginning of the end for ISIS may well take place in Syria. But it will take strategic focus, diplomatic discipline, and operational excellence. For the Obama administration, the question is less “can we do it” than “will we even try?”