When U.S. President-elect Donald Trump is inaugurated on January 20, 2017, his most complicated foreign policy challenge will be what to do about Syria. Under President Barack Obama, Washington’s Syria policy has focused on fighting the Islamic State of Iraq and Syria (ISIS). But with ISIS teetering, the government of Bashar al-Assad gaining ground, and outside powers such as Iran and Russia becoming ever more involved, simply fighting the caliphate may not be enough for the next leader of the United States.

In order to destroy ISIS and uproot the extremism that has been generated by the Syrian war, the United States will need to help stabilize opposition-controlled areas of the country while pressuring Iran and Russia to move toward a viable political settlement. To get there, President Trump will need to be more willing to put pressure on Moscow and Tehran than he has so far indicated. That means he should be ready to impose penalties on both if they do not fulfill any commitments they make.

A FRAGILE EQUILIBRIUM

Today, ISIS and the Assad regime each control roughly one-third of Syria. Thanks to help from Russia and Iranian-backed Shiite militias, the Syrian government has established control over what it calls “essential Syria”: the urbanized, north–south spine of the country that connects Damascus to the country’s largest city, Aleppo, which Assad is now on the verge of reconquering. But if he is successful, what happens next is unclear. Assad claims he will reassert control over the entire country, but he lacks the manpower to take and hold Sunni-dominated territory in northwestern, eastern, and southern Syria. He could only do so by importing more Shiite militiamen from abroad, which could provoke Syria’s neighbors to increase their involvement and fuel the local Sunni insurgency.

Eastern Syria has, for the last two years, been split between ISIS and the Kurdish People’s Protection Units (YPG), part of the Syrian wing of the Turkish Kurdistan Workers’ Party (PKK), which Ankara considers a terrorist group. The Syrian Democratic Forces (SDF), a U.S.-backed alliance made up mostly of YPG troops interspersed with Sunni Arabs and minorities, has so far been Washington’s only option for fighting ISIS in the region. But in late August, Sunni Arab and Turkmen rebels, backed by Ankara and supported by the Turkish military, entered northeastern Syria as a part of Turkey’s Operation Euphrates Shield. These units rapidly capturing ISIS-held areas near the Turkish border.

Ankara’s entry into the Syrian war is the most significant (and potentially destabilizing) development since ISIS’ breakout in 2014. The move is designed to crush two enemies at once. First, Ankara wants to prevent the YPG—which the Turkish government sees as an extension of the terrorist PKK—from uniting the Kurdish-held areas in the east, around the town of Manbij, with those in the west in the canton of Afrin. Second, the Turks want the area to serve as a potential staging ground for further military operations against ISIS. Some speculate that Turkey intends to attack from north of the SDF-held Syrian city of Tal Abyad, the northern gate into ISIS’ capital city of Raqqa. As a result, both the SDF and Ankara have issued a flurry of announcements, with each side claiming that it will be the first to liberate Raqqa.Ankara’s entry into the Syrian war is the most significant (and potentially destabilizing) development since ISIS’ breakout in 2014.

The best-case scenario is that either the SDF or Turkey will be able to wrest Raqqa from the caliphate, delivering a much-needed blow to ISIS. The Kurds have the advantage of U.S. support and unity of purpose, but are relatively few in number and have little desire to take and hold Raqqa, which is largely populated by Sunni Arabs who distrust or even despise the Kurds. Euphrates Shield has the advantage of Sunni Arab foot soldiers and the backing of a NATO army, but it has received little support from Obama and his ISIS czar, Special Envoy Brett McGurk. But the worst-case scenario is that the SDF and the Turkish forces fight each other instead, leaving ISIS in control of the east and Assad secure in the west.

WEST OF EDEN

In the west of the country, a similar territorial division persists, this time between the Assad regime and assorted non-ISIS rebels. The rebels control the northwestern canton of Idlib and areas of Aleppo province, as well as cantons in the southern provinces of Dara’a and Quneitra. Each rebel-held canton is a mix of local militias, jihadists, and non-jihadist Salafists. The most notable of the jihadist groups—outside of ISIS—is Jabhat Fatah al-Sham (JFS), the Syrian al Qaeda affiliate formerly known as Jabhat al-Nusra. As anti-regime Syrians have come to doubt Washington’s commitment to removing Assad, more and more have opted to join JFS.

The rapid growth of JFS in the northwest has caused many, including Secretary of State John Kerry, to advocate for a deal involving synchronized U.S.–Russian air strikes against the group, which if carried out would seem to benefit Assad. But his regime is now estimated to have only about 20,000–25,000 deployable troops. That is enough to surround east Aleppo and some rebel-held suburbs of Damascus, but only with help from Hezbollah and other Shiite militiamen from Afghanistan and Iraq. To pursue its siege-and-starve strategy elsewhere in Syria, the regime will need to import more Shiite fighters from abroad. These militias, however, are often poorly trained and have trouble operating in the rural Sunni parts of Syria.

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The United States will be lucky if the rebels can somehow resist Assad’s siege of Aleppo and the Trump administration can convince the Russians to resume the cessation of hostilities agreement, which fell apart in September. But that is unlikely. More probably, the Assad regime, aided by the Russians, will continue bombing east Aleppo, thereby worsening the flow of refugees into Syria’s neighbors and sending Assad’s opponents further into the arms of JFS and other extremists. Such an outcome would bolster Moscow’s case for making Assad the basis for a solution in Syria. It could also expand Russia’s role in the eastern Mediterranean for years to come.

USING THE BIG STICK

Until now, U.S. policy has remained committed to the unity of Syria under UN Security Council Resolution 2254, which reaffirmed the “sovereignty, independence, unity, and territorial integrity of the Syrian Arab Republic.” But Syria has been divided for half a decade, and to deal with it, the United States will need to uproot extremists and provide humanitarian protection to the country’s component parts, with an eye toward putting them back together again. To achieve that, there are five major tactical options that the Trump administration could apply to Syria: no-fly/ safe zones; anti-regime airstrikes to enforce the ceasefire; arming of the vetted opposition; sanctions; and diplomacy. Whatever the combination, these tactics should be employed to reduce U.S. vulnerability to extremism and migration (which is driven by the conflict), recognizing that doing so may require a willingness on Washington’s part to tolerate the risks associated with using force.

The first option, the establishment of limited no-fly/safe zones, has already received some support from both Trump and Vice-President-elect Mike Pence. Announcing the intention to establish no-fly/safe zones would signal to Assad that the new administration does not believe he can actually retake “every inch” of Syrian territory. Of course, a no-fly zone over the entire country would require the United States to attack Syrian and Russian air defense systems—something no president is likely to do given the threat of war with Russia. However, limited no-fly zones along Syria’s borders with Turkey and Jordan already exist, and Turkey’s de-facto safe zone north of Aleppo is an example of how these areas can be blocked off without military confrontation. A smart U.S. strategy would involve deploying special forces to shore up safe zones on the ground and using air strikes and cruise missiles to target regime aircraft and artillery.

Another similar military option would be to use long-distance air strikes to enforce the ceasefires that have repeatedly fallen apart. Ceasefires only work when the parties have positive incentives to negotiate, and sufficiently strong negative incentives not to break the ceasefire. Thus far, Assad and the Russians have been able to punish the opposition, but not vice versa. The United States could help even out the balance of power by punishing the regime with cruise missiles, or airstrikes on regime airfields. This risks inadvertently killing Russian soldiers, but the concentration of Russian forces in a few geographical areas ensures that there are multiple targets within the country—runways, artillery positions, and exposed jets and helicopters—that could be safely attacked by the United States from outside Syrian air space.

Alternatively, the United States could provide qualitatively new weapons in larger amounts to the vetted Syrian opposition—something the Obama administration has been unwilling to do. Controlling territory requires manpower, and given the Assad regime’s limited numbers and the growing influence of extremists, it is important to support the remaining elements of the non-jihadist rebels. Such support would only work, however, if the United States commits to fighting the Assad regime, an option that Obama has sought to avoid and that Trump at this point looks unlikely to pursue.

The United States can also consider deepening sanctions. Doing so would help the United States gain much-needed leverage in future negotiations, allowing Washington to raise the penalties faced by Assad and create incentives for him to accept a real political transition in Syria that would unite the country. This is particularly important given the regime’s desperate need to rebuild infrastructure and the urban areas that it has destroyed. A missing but vital aspect of this diplomacy should include prosecution for war crimes, particularly for the use of chemical weapons.

U.S. diplomacy has so far come up short in terms of forcing Assad to step aside.

It has also failed to give the Russians and the Iranians a reason to jettison their client.

A final option is diplomacy, whether coercive or otherwise. U.S. diplomacy has so far come up short in terms of forcing Assad to step aside. It has also failed to give the Russians and the Iranians a reason to jettison their client. Military force and sanctions would strengthen the negotiators’ hand, but more targeted diplomacy with allies, as well as hardnosed negotiations with adversaries, would provide a much-needed shot in the arm to fortify efforts to end the war.

THE ART OF THE DEAL