Turkey and Russia reached an agreement at the September 17 Sochi Summit that has postponed, but not precluded, a threatened Syrian–Russian–Iranian offensive against Idlib province, the last major stronghold of Syrian rebels. The vague agreement is a work in progress that is likely to collapse, as many previous Russian diplomatic arrangements in Syria have collapsed—Moscow discards them when it suits its interests. Turkey is being set up to fail. It is required by the agreement to eliminate Islamist extremist factions that dominate the fragile rebel coalition in Idlib, an extremely difficult task. After it fails, Moscow is likely to discard another agreement and resume the military campaign against Idlib.

The U.S. should seek to deter a humanitarian disaster through diplomatic means and should not use military force unless U.S. troops in eastern Syria are threatened, or Syrian dicatator Bashar al-Assad once again uses chemical weapons. Washington should push for a long-term political settlement that would defeat the Islamic State (ISIS) and other Islamist extremist groups, as well as contain Iran, by using its military presence and reconstruction aid as leverage.

A Temporary Reprieve for Idlib

The Idlib region is the last of four “de-escalation zones,” which were established by Russian-brokered diplomatic agreements that masked Russian President Vladimir Putin’s strategy for eliminating rebel strongholds one by one. The separate agreements enabled the Assad regime’s survival through a divide-and-rule strategy. After the three other de-escalation zones were conquered, more than one million Syrians fled to Idlib, boosting the province’s population to over 3 million people.

There are an estimated 70,000 rebel fighters in Idlib province. Hayat Tahrir al-Sham (HTS), a front organization whose dominant faction is the al-Qaeda-linked Jabhat al-Nusra, is the strongest insurgent force with about 10,000 fighters, of which an estimated 20 percent to 30 percent are foreign fighters who have nowhere else to go.

Turkey, a longtime supporter of many Syrian rebel groups, seeks to preserve a zone of influence in northern Syria to act as a buffer zone limiting the threat of Kurdish groups, ISIS, and other Islamist extremists. Turkey established at least 12 observation posts in Idlib, where it has deployed hundreds of troops, supported by armor and artillery. Ankara reinforced its positions in Idlib and boosted supplies to allied rebel groups there when an offensive seemed imminent, signaling Turkey’s willingness to take risks to defend the territory.

Turkey has reshuffled parts of the rebel coalition in Idlib to form the National Liberation Front, an umbrella group that loosely unites factions with about 20,000 fighters, including remnants of the Free Syrian Army. Turkey is trying to dissolve HTS or at least encourage defections in order to weaken it.

Turkey also wants to prevent another influx of refugees, similar to the 2015 wave. It already hosts more than 3.5 million and seeks to secure their return to Syria. But Syria’s Assad regime does not want all of the refugees to return; it considers most of them to be terrorists.

The Idlib campaign would quickly become a massive humanitarian catastrophe. Russian bombing could send another wave of refugees to the Turkish border, just as previous Russian bombing campaigns helped to push more than 5 million Syrians to flee the country.

The Idlib campaign would be a grueling and costly one for Syria’s depleted army. Battle-hardened rebel groups have had months to entrench themselves in mountainous terrain. Foreign fighters have no place to go and are likely to fight to the end. It is not clear that the Syrian–Iranian coalition has the military muscle to invade and conquer Idlib without resorting to chemical weapons, as it has done many times in the past. The delayed offensive gives the regime more time to assemble the necessary ground forces, but it will remain dependent on Iranian-led militias to stage ground offensives, and dependent on Russia for air support.

Ticking Time Bomb. The Sochi agreement requires the withdrawal of what Putin referred to as “radically minded rebels” from a 15 kilometer to 20 kilometer demilitarized zone that will be jointly patrolled by Russian and Turkish troops. It is unclear how to differentiate “radically minded rebels” from other armed opposition forces. Both Putin and Assad consider almost all rebel groups to be terrorists. Putin gave Turkey time to eliminate or compel the withdrawal of “radically minded rebels,” but Ankara is unlikely to do so to Moscow’s satisfaction, and is certain to fall short of Assad’s demands.

Turkey has acceded to Russia’s unrealistic goals: to disarm HTS and other Islamist extremist groups, evict them first from the demilitarized zone and then from all of Idlib, strip heavy weapons from rebel groups, and eventually re-open roads for regime convoys. HTS and other extremist groups, who control the bulk of rebel-held territory in Idlib, have failed to withdraw from the proposed demilitarized zone or disarm. Turkey’s rebel allies have cautiously accepted the deal but are dragging their feet on giving up their heavy weapons.

HTS, the Assad regime, and Iran are likely to try to sabotage the bilateral Russian–Turkish agreement. Assad has pledged to reconquer every inch of Syria and will not be satisfied with the status quo. There already have been violations of the agreement by both sides and regular artillery exchanges. It is just a matter of time before all-out fighting resumes.

The Sochi agreement is therefore a temporary and conditional reprieve, not a sustainable peace accord. The pause in the fighting, however, serves Moscow’s interests by underscoring Russia’s role as the primary arbiter of Syria’s future, defusing international criticism ahead of the opening of the U.N. General Assembly and giving the Assad regime more time to prepare for a final offensive.

How Washington Can Help

The Trump Administration correctly has made the defeat of ISIS its highest priority in Syria. Despite the abhorrent nature of the Assad regime, its long record of hostility to the U.S., and its support of terrorism, ousting it through military action would have been a prohibitively costly and risky goal. Washington should recognize that the Assad regime has won a pyrrhic victory over the fractious rebel camp. Regime change is not a suitable U.S. military objective. As Ambassador James Jeffrey, the U.S. Special Representative for Syria Engagement, has stated: “Assad has no future, but it’s not our job to get rid of him.”REF

The Assad regime will cling to power, backed by Russia and Iran, but will be permanently delegitimized by its war crimes, including the use of chemical weapons against its own people. Washington’s top priorities should be deterring the regime’s use of chemical weapons, defeating ISIS and al-Qaeda in Syria, and preventing Iran from exploiting the carnage in Syria to threaten Israel and Jordan.

The principal source of U.S. leverage is the deployment of about 2,200 troops in eastern Syria, where they train, equip, and advise the Syrian Democratic Forces, a Kurdish-led coalition that did the bulk of the fighting on the ground against ISIS. These forces, backed by U.S. air power, are the chief barrier to the resurgence of ISIS, as well as Syrian and Iranian forces, in eastern Syria. But U.S. ties to Syrian Kurds are resented by Turkey, which sees them as a greater threat than ISIS because of their ties to Kurdish separatists in Turkey, which Ankara has been fighting off and on since the 1980s.

The Trump Administration in July acquiesced to the Assad regime’s re-occupation of the southwestern de-escalation zone established in Daraa province. But the Administration has taken a harder line in opposing an offensive in Idlib province under the new Syrian team led by Ambassador Jeffrey. Before the threatened Idlib offensive was postponed, President Donald Trump tweeted on September 3: “President Bashar al-Assad of Syria must not recklessly attack Idlib Province. The Russians and Iranians would be making a grave humanitarian mistake to take part in this human tragedy. Hundreds of thousands of people could be killed. Don’t let that happen!”

To advance U.S. interests in Syria, Washington should:

• Focus on defeating ISIS and al-Qaeda, while containing Iran. Idlib has become the largest sanctuary for al-Qaeda-linked fighters since pre-9/11 Afghanistan. The U.S. has a vital interest in defeating al-Qaeda, HTS, and ISIS, but the brutal tactics employed by Russia, Syria, and Iran are likely to backfire. Russia’s scorched-earth strategy for defeating Islamist extremists in Chechnya helped to radicalize many Chechens and drove them to join Islamist insurgencies in Afghanistan, Iraq, and Syria. The indiscriminate brutality of the Assad regime will push many Syrians deeper into the arms of HTS and other extremist groups. The deployment of Iran’s Shia foreign legion—more than 20,000 radical Shia fighters in militias recruited from Lebanon, Iraq, Afghanistan, and Pakistan—will fuel sectarian tensions and trigger a Sunni backlash, helping ISIS and al-Qaeda to resurge in the future.

  Washington therefore has an interest in staving off a Syrian–Russian–Iranian offensive in Idlib and buying more time for Turkey to undermine HTS. Preventing a Syrian offensive could also avert another wave of Syrian refugees and mitigate the ongoing humanitarian crisis in Idlib. Washington should help Turkey by providing intelligence and counterterrorism targeting support for rooting out HTS and other extremists in northern Syria. In exchange, Washington should press Ankara for help in defeating ISIS and preventing its return. This should include halting Turkish attacks on territory controlled by America’s Kurdish allies, which divert them from fighting ISIS. U.S. efforts to broker a non-aggression pact between Turkey and Syrian Kurdish groups, similar to the arrangement Turkey reached with Iraqi Kurdish groups, could advance the security interests of all sides.

  Washington should retain its military presence in eastern Syria until ISIS has been decisively defeated. It should not withdraw its limited military contingent until a satisfactory political settlement for Syria has been hammered out, which addresses the legitimate concerns of Syria’s Sunni majority without forcing Sunni Arabs back into the arms of ISIS or al-Qaeda, and requires the withdrawal of Iranian Revolutionary Guards and Iran-led militias.

  Iran is unlikely to be forced out of Syria by military pressure, but might be induced to withdraw its military forces as part of a political settlement that leads to a U.S. withdrawal. Until such a settlement can be negotiated, Washington should maintain its military presence to preclude a resurgence of ISIS and deny Iran control of the most direct land supply routes between Tehran and Damascus. The U.S. also should strongly back Israel’s efforts to defend itself by preventing Iran from entrenching itself in Syria.

• Deter Damascus from using chemical weapons. The U.S. intelligence community reportedly concluded that the Assad regime was preparing for the possible use of chemical weapons in Idlib. If that happens, the Trump Administration should launch air strikes against Syrian forces responsible for the attack, as it has twice before, in April 2017 and April 2018, when Assad was caught red-handed using chemical weapons.

• Seek a long-term political settlement. Washington should keep its distance from the Russian-brokered talks in Astana, Kazakhstan, which is designed to secure the Assad regime’s future, not genuine peace in Syria. The U.S. instead should seek to revive the U.N.-sponsored Geneva negotiations, which have been on life support in recent years. Geneva could become the diplomatic path to an acceptable end state in Syria. But more U.S. leverage is needed to budge Assad. Washington should seek to leverage not only the continued U.S. military presence, but also American and allied aid for Syrian reconstruction. Until an acceptable political settlement for Syria is reached, which facilitates the permanent defeat of ISIS, HTS, and other Sunni extremists, as well as the withdrawal of Iran, Hezbollah, and other radical Shia forces, the U.S. and its allies should withhold any aid for reconstruction in territory controlled by the Assad regime. This linkage would put greater international pressure on Moscow and Tehran, which are burdened with mounting war costs, and cannot afford to finance rebuilding on the scale required.

Needed: A Genuine Peace Agreement

The Sochi agreement, which has been prematurely hailed as a diplomatic success, is bound to fail. Turkey gained an 11th-hour reprieve for Idlib province that inevitably will fall apart. The U.S. should prioritize the defeat of ISIS and other Islamist extremists, along with containing Iranian influence, while ruling out the use of force against the Assad regime unless it threatens U.S. forces or uses chemical weapons. Ultimately, U.S. national interests would be best served by pushing for a political settlement of Syria’s bloody civil war that will undercut regional support for Islamist extremism, of both the Sunni and Shia varieties.

—James Phillips is Senior Research Fellow for Middle Eastern Affairs in the Douglas and Sarah Allison Center for Foreign Policy, of the Kathryn and Shelby Cullom Davis Institute for National Security and Foreign Policy, at The Heritage Foundation.