It seems as though there is only so much a brokered cease-fire in Syria can actually achieve. On Sept. 19, mere hours after a weeklong cessation of hostilities ended, an aid convoy — coordinated by the United Nations, bearing the requisite permits to venture into rebel territory — was bombed from the air in western Aleppo province. U.S. officials on Tuesday implicated that Russia was responsible for the strike, even citing intelligence showing that two Russian Su-24 attack aircraft were directly over the convoy at the time of the attack. Moscow continues to deny any involvement, claiming that a fire caused the reported damage to the convoy. The United Nations quickly called off the delivery of any additional humanitarian aid, and in doing so called into question the likelihood that anyone in Aleppo will get the help siege warfare typically does not afford.
The United States and Russia each had their own reasons for brokering the cease-fire — without mutual interest, it never would have been implemented in the first place — but their reasons differed markedly. Though the delivery of humanitarian aid was one of Washington's most important stipulations, the ultimate objective was to continue the fight against the Islamic State. Negotiating an end to the Syrian civil war, thereby denying the jihadist group a vacuum in which to operate, is a necessary component of that fight's success. Washington was therefore willing to concede to some of Russia's demands, even if its demands weakened the rebels who oppose Syrian President Bashar al Assad, if doing so put U.S. forces closer to defeating the Islamic State.
The Russians, for their part, were not as interested in the Islamic State. They continue to be much more interested in preserving the Syrian government — in fact, they care more about its success than the Americans care about the success of the rebels. Moscow also had an ulterior motive: Coordinating more closely with Washington in Syria could inform its behavior when it negotiates with Washington in Ukraine, the site of a geopolitical conflict much more important to Russia's existence than Syria, and over the issue of sanctions. (And a deal with the United States, moreover, enhances Russia's status in the Middle East.)
As difficult as it was to reach a deal, reach one they did on Sept. 9. But the success or failure of the deal was always going to depend less on Russia and the United States and more on how the combatants responded to it. Persuading such a variegated group of people to agree on anything was already a tall order. But when Moscow and Washington added a clause whereby their militaries would jointly target Jabhat Fatah al-Sham, one of the most effective, albeit extreme, rebel groups, it became clear that the rebels were going to actively undermine a deal that put them further away from achieving their goal: toppling al Assad.
All told, the cease-fire benefited the loyalists more than anyone else. Still, they were bound to object to some of the clauses in the agreement, including ones that limited the use of Syrian air power and, unsurprisingly, the delivery of humanitarian aid, which directly undermined their efforts to starve out rebel strongholds. And in any case, the Syrian government's command and control structure has decayed through years of constant war. So even if its leaders did not object to some aspects of the agreement, there was no guarantee that the more independent militias would receive, let alone follow, their orders.
These constraints became readily apparent in the first seven days of the cease-fire. Violations were steadily made, humanitarian aid largely failed to reach besieged areas, and rebel groups outright refused to distance themselves from Jabhat Fatah al-Sham. The airstrike that struck the convoy, not to mention a separate strike that hit loyalists in Deir el-Zour, only sealed the fate of an already dying agreement. And, just as important, they represent the shattered trust between the powers abroad that broker deals and the powers on the ground that must abide by them.
On Sept. 21, the U.N. Security Council will probably discuss how to move forward in Syria. (As a matter of fact, U.S. Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov are slated to meet throughout the week.) Considering how resolutely the previous one seems to have failed, the chances for another cease-fire seem pretty remote. But the underlying reasons that outside powers would want to reach one remain, so progress can never be ruled out entirely. Just as last February's cease-fire cast a shadow over the most recent attempt at resolution, last week's cease-fire casts an even longer one over whatever discussion the Security Council may have in the coming days.