After months of negotiation, a nationwide cease-fire agreement reached between Russia and the United States will take effect in Syria at sunset Sept. 12. Though violations of the truce are bound to occur, the deal will at least reduce violence in the beleaguered country for the time being. Having encircled the rebel-held parts of eastern Aleppo after suppressing a rebel counteroffensive, Russian- and Iranian-backed loyalist forces are more likely to abide by the agreement than their opponents in the rebel camp will. The loyalist factions will use the cease-fire, which excludes some rebel groups including Jabhat Fatah al-Sham (formerly known as Jabhat al-Nusra), to divide and weaken rebel groups as much as possible. Meanwhile, the United States will try to isolate Jabhat Fatah al-Sham on the battlefield for joint targeting with the Russians.

Even as rebel groups cautiously accept the cease-fire, however, it is unlikely that the Turkish- and Qatari-backed Ahrar al-Sham and the Saudi-backed Jaish al-Islam will cut ties with Jabhat Fatah al-Sham, a formidable and pervasive force on the battlefield. Saudi Arabia, in particular, is wary of a closer alignment between Moscow and Washington that leans in Iran's favor and will push to fortify its own rebel factions during the temporary calm. Turkey, on the other hand, stands to gain from the deal. The less the rebel groups it supports have to worry about being pummeled by Russian-backed loyalists, the more Ankara can steer their focus toward containing Kurdish People's Protection Units. Turkey, moreover, is strategically piggybacking on the U.S.-Russian negotiations to smooth out possible complications with Russia that could arise on the battlefield.

The cease-fire is a preliminary step and still quite tenuous. As the truce progresses, it could create schisms among the rebel forces and their foreign sponsors. If the agreement endures and evolves into renewed discussion over a power transition for Syria, then Iran, Saudi Arabia and Turkey will begin bargaining to determine the conditions of Damascus's future. In fact, the subject will likely be a topic of discussion when Iran's deputy foreign minister for Arab and African affairs meets in Moscow with his Russian counterpart on Sept. 13.