Government-held West Aleppo is secured and rebel-held East Aleppo is under siege—again. While the United States and Russia haggled over humanitarian access and truces, Syrian army forces, backed by the Russian aircraft and Shia foreign fighters, broke through Sunni rebel lines near the Ramouseh area of Aleppo.

Some suspect that U.S.-Russian or Russian-Turkish agreements may have influenced the developments on the battlefield. While rebel leaders deny this and say they simply faced overwhelming odds, the defeat in Ramouseh is undoubtedly connected to Turkey in one way: the Turkish use of Syrian rebels as a proxy force against the self-declared Islamic State and Kurdish forces has drawn many fighters away from their war against President Bashar al-Assad, weakening opposition lines in Aleppo.

No Rebel Sermons Just Yet

For nearly a whole month, the Jaish al-Fateh coalition of Islamist rebels from Idlib and Aleppo has held the area around the Artillery Faculty and the Ramouseh neighborhood, reportedly with Turkish backing. The rebels thereby severed West Aleppo from its main supply road to Hama and created a corridor between East Aleppo and the opposition-controlled countryside. For the rebels, taking the Artillery Faculty in early August turned defeat into victory, rekindling hopes of ultimately triumphing in the city.

“The battle is not about breaking the siege, breaking the siege was the beginning of the battle! God willing, the battle is about holding our next sermon in the Saadallah al-Jabri Square,” roared the Saudi jihadi preacher Abdullah al-Moheisini in a propaganda clip from Ramouseh, referring to the famous square in central Aleppo.

But now that the Artillery Faculty is back under Assad’s control, no jihadi sermons will soon be held at Saadallah al-Jabri Square.

A Costly Victory for Assad

For Bashar al-Assad, who lost hundreds of troops trying to expel the rebels from the Artillery Faculty, the battle must have served as a costly lesson about the importance of protecting your flanks. The area reportedly fell to Jaish al-Fateh in August because the army had withdrawn to fight on other fronts. This left a placeholder force of local militia that ended up fleeing its positions.

Assad’s fundamental problem is that he lacks enough troops to be everywhere at once. Not even the thousands of Shia Islamist volunteers pouring in from Iraq, Iran, and Lebanon have been able to compensate for this manpower problem. It leaves Assad with the options of limiting his territorial ambitions or making risky gambles. Aleppo was a gamble. It now seems to have paid off—but it very nearly didn’t. Indeed, just as the army prepared to seize the Artillery Faculty in early September, it was forced to divert forces to northern Hama where another rebel offensive had begun to chip away at loyalist territory. Though the government later managed to break through rebel lines, the price was high and the situation remains precarious. Jaish al-Fateh is not likely to give up the battle and may yet launch a counter-offensive or find another chink in Assad’s armor. Russian-American attempts to reach a diplomatic deal over Aleppo could also bring changes to the battlefield, perhaps not all to Assad’s liking.

But for the time being, assuming the army succeeds in holding the line in Hama, the situation has largely reverted to what it was in July. Rebel-held East Aleppo is again firmly under siege and Assad has secured his access to West Aleppo, leaving him clearly ascendant in the north. Although he has faced setbacks around Hama, Assad’s forces have recaptured Darayya and Moadhamiyeh west of Damascus, and they continue to advance in the East Ghouta.

In other words, other than the hiccup in Hama, Assad seems to be cementing his hold on what some have termed “useful Syria.” If this continues, with opposition forces driven into besieged cities and rural regions, it is likely to have implications for how the Syrian conflict is understood and managed by outside actors.

Rebel Needs, Turkish Priorities

The Syrian rebels will also draw lessons from what happened. The most obvious reason for their defeat at the Artillery Faculty was the disparity of power between Jaish al-Fateh and allied groups, on the one hand, and the combined forces of Syria, Russia, Iran, and Hezbollah, on the other. This is disheartening enough, but the rebels are also likely to draw other troubling conclusions from what transpired in Aleppo.

One is that the proxy problem is now beginning to bite. A rare piece of good news amid the gloom for Syrian rebels was their September 4 victory along the Turkish border northeast of Aleppo, where they fought under the leadership of Turkish special forces to drive out the Islamic State and anti-Turkish Kurdish groups. The Turkish intervention, which began on August 24, aims at creating a buffer zone to push the Islamic State away from the border—this is a longstanding U.S. demand—while also forestalling the creation a contiguous Kurdish-held region in northern Syria. Both of these goals are shared by the Syrian rebels, but they are not as much of a priority for them as holding the line in Aleppo. Yet rebels from the Aleppo region were pushed by Turkey, and paid, to stay on the border front, instead of returning to their home city to fight.

Credible figures are hard to come by, but some estimate that between 1,000 and 5,000 Syrians took part in the initial intervention on August 24, most of them drawn from U.S.-vetted nationalist and soft-Islamist groups operating under the Free Syrian Army banner. Thousands more were located in another border pocket, near Azaz, and have since joined Turkey’s border-clearing operation. For comparison, Reuters estimated the Jaish al-Fateh-led main force that seized the Artillery Faculty at around 6,000-8,000 fighters. Though the Syrian rebels will likely profit from the Turkish border zone in some ways, it seems certain that they would have gained more from these troops by putting pressure on Assad in Aleppo. But Turkey had other plans, because it has a different set of priorities—and in the end, thousands of fighters opted to follow Ankara’s lead.

Already, about a dozen air forces have bombed Syria since 2014 and tens of thousands of foreigners are now fighting on its soil. As the Syrian war has become more internationalized, such mismatched patron-proxy relationships are only likely to become more common.