Displaced Syrians leave Idlib in January.Omar Haj Kadour / AFP / Getty

A disaster seemed imminent in Syria’s Idlib province. Bashar al-Assad, the president of Syria, had massed his forces on the borders of the province, the last major rebel stronghold in the country, while Syrian-government and Russian warplanes bombarded towns and villages along the front lines. It appeared to be a grim replay of the sequence of events that has brought other rebel-held areas under Assad’s sway—only this time, it was playing out in an area that is home to nearly 3 million people with nowhere to flee. “The nightmare scenario … is that the regime and the Russians drive well over 1 million people toward the [Turkish] border,” one Western diplomat told me. “There’s no space for them, and they try to cross the border or get bombed trying to do so.”

Today, in a bid to avert the impending disaster, Russia and Turkey signed a “memorandum of understanding” that aims to create a buffer zone between Syrian government forces and rebel fighters. As part of the agreement, terrorist groups such as the al-Qaeda-linked Hayat Tahrir al-Sham must pull out of the zone, while other parties must withdraw their heavy weapons. Turkey, the opposition’s primary backer in Idlib, maintains 12 observation posts there and recently rushed tanks and howitzers to the border and increased military aid to friendly rebels. Russia’s defense minister also said bluntly that there will be no military operation in Idlib. But a confrontation between the two powers in northern Syria still seems inevitable: Vladimir Putin, the president of Russia, recently called for “the total annihilation of terrorists in Syria.”

From Moscow’s perspective, the agreement offers several advantages. It prevents a total rupture in its relationship with Ankara, an influential regional player with whom it wants to work on a number of other fronts. A dramatic offensive in Idlib would have sparked an international backlash both against Russia itself and against the Syrian government, whose reputation Moscow has been trying to rehabilitate in international circles in order to pave the way for foreign investment in the reconstruction of the war-torn country. “If this assault goes forward, and if this results in a massacre of civilians, which we believe will be the case, Russia is complicit,” the diplomat said.

The reconquest of Idlib also represents a massive undertaking for Assad and his Russian allies. The size of the operation would dwarf other government offensives: The province is roughly the size of Delaware, encompassing an area of more than 6,000 square kilometers. By comparison, the 2016 struggle to wrest East Aleppo from rebels occurred over 45 square kilometers that were home to a population one-tenth the size of Idlib’s, while the government offensive in southwest Syria earlier this year was fought over approximately 3,000 square kilometers, containing roughly one-quarter the number of people who now reside in Idlib. The sheer scope of the offensive explains why the United Nations warned that Idlib potentially represents the “worst humanitarian catastrophe” of the 21st century.

The new agreement, however, may represent only a temporary reprieve for Idlib. It remains unclear, for example, how Turkey is going to compel radical rebel groups to withdraw from the buffer zone. Russia is also pressuring Turkey to separate these groups from rebel groups it supports across Idlib, but there is little indication that Ankara can accomplish this. While Putin and Recep Tayyip Erdoğan, Turkey’s president, seem interested in first collaborating on other fronts where their interests overlap—notably to weaken the Kurdish-led Syrian Democratic Forces—this will not alter their fundamental disagreement over Idlib.

Russia and other regional powers have previously agreed to “de-escalation zones” in Syria that succeeded in temporarily tamping down violence, only to be discarded when the interests of Moscow and the Syrian government changed. Nour Hallak, an anti-government activist, and those like him fear that this current agreement could follow the same course: Assad and his allies could opt for an incremental approach to the Idlib operation, as Russia attempts to use it as leverage to compel the opposition’s allies to concede to a political settlement on Moscow’s terms. “We will probably see minor clashes in the next several months, and attempts by the regime to take territory by small bites,” Nikolay Kozhanov, a former Russian diplomat and an academy associate at Chatham House, said. “Russia will use this to put pressure on the Europeans, but it is not now interested in a full-fledged military operation.”

Nor is Russia’s strategy in Idlib necessarily set in stone. The Kremlin’s best-case scenario, Kozhanov said, is that the entire province returns to Syrian government control: It wants to prevent the United States from throwing its weight behind opposition forces in the future, thus endangering its position in the Middle East. But at the same time, there are limits to the number of soldiers and resources that Putin is willing to pour into Syria. If rebel fighters successfully resist government advances, and the operation seems likely to spark a significant reaction from Turkey or the United States, Kozhanov said Russia “will be ready and prepared for much more concessions toward Turkey.”

There is no question, however, about Assad’s ultimate goal. Foreign Minister Walid al-Muallem said recently that the Syrian military would “go all the way” in Idlib, and that foreign aggression “will not influence our determination to liberate the entire Syrian territory.” If the Syrian government is determined to press forward in Idlib, it could well drag Moscow along with its plans.

For civilians in Idlib, the fact that an offensive could come in weeks or months, rather than days, offers little comfort. Many fear retribution should Assad reestablish control over the province. While they have become inured to air strikes after years of such attacks, the prospect of a ground invasion represents an entirely different threat. “We are fine with shelling, but not fine with the regime reconquering Idlib,” Hallak told me. “We’re afraid Assad is going to commit massacres. He’s going to torture and kill people.”

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