An airstrike hits an outdoor market in Idlib, leaving a child’s severed torso lying in the street among scattered plasticware and household items. Another hits a residential neighborhood in Aleppo sending a stream of wounded people to the hospitals. Shelling kills a woman and three children outside of Damascus. Hours after the United States and Russia announced an agreement for what Secretary of State John Kerry called “a genuine reduction in violence” in Syria, the regime of president Bashar al-Assad responded with what appeared to be a surge in violence on Saturday.

The renewed shelling and airstrikes in rebel-held sections of Syria comes two days before the agreement is set to go into effect, in time for the Muslim Eid al-Adha holiday. For Syrians living the reality of a conflict that has already killed as many as half a million people, the strikes illustrated deep and widespread doubts about whether the new accord would ease their suffering. Dozens of people were killed in strikes in at least three separate opposition-held areas, according to medics and first responders.

“I will tell my expectations for the coming two days. Assad will try kill as much as possible before the claimed ceasefire. A lot of shelling and bombs will fall upon civilians, especially the almost empty markets,” said Abdulkafi Alhamdo, an English teacher living in the besieged opposition sector of Aleppo, in a text message.

Kerry and Russian foreign minister Sergei Lavrov announced the agreement at a news conference after midnight on Saturday following long hours of negotiations in Geneva. No text of the agreement as been made public, but Kerry described the terms of the deal in broad terms. The agreement calls on Russia to restrain the Assad government, with whom it is allied, from carrying out indiscriminate attacks in opposition-held areas. Following a seven-day “period of reduced violence,” the agreement then calls for the U.S. and Russia to work together to launch strikes against both ISIS and al-Qaeda’s affiliate in Syria, formerly known as the Nusra Front.

The agreement comes nearly a year after Russia intervened in Syria, unleashing a devastating campaign of airstrikes that strengthened Assad’s campaign to reclaim key areas of the country lost to the rebels and jihadist groups over five years of war. If it succeeds, the accord would have the US cooperate in a more targeted air war that singles out extremist groups.

In Syria, the announced agreement raised more questions than it answered. One key question is how the U.S. and Russia would implement the plan to cooperate on airstrikes against Nusra. Unlike ISIS, Nusra is allied with other, more mainstream rebel groups. The group announced a formal split with al-Qaeda in July, and in August it played a central role in a rebel alliance that succeeded in breaking the siege of the opposition-held section of the city of Aleppo, a move that won it some public support in the long-suffering rebel-held section of the city. The group also re-shaped its own public image, and now calls itself Jabhat Fateh al-Sham.

Nusra’s presence among other opposition groups poses a dilemma that has contributed to the failure of past ceasefires. Speaking to reporters in Geneva, he argued that the agreement would make it harder for the Assad regime to “mask attacks against the legitimate opposition by claiming that it’s going after Nusrah.” He also issued a warning to rebel groups who are allied with the jihadists.

“So the warning we give to opposition groups who have up until now found it convenient to sort of work with them is it would not be wise to do so in the future. It’s wise to separate oneself,” he said.

The question then is whether other rebel groups can and will divorce themselves from Nusra, which is the strongest force in some opposition-controlled areas. Alliances among opposition groups are chaotic and shifting, posing dilemmas both for the rebel groups on the ground and for the U.S. and Russian militaries who now plan to work together to pinpoint Nusra targets.

“In practical terms, I think there are limits to how much the rest of the opposition can effectively distance itself from Nusrah, particularly in the northwest. They’re just too mixed, not just in terms of geographic control – in one town, you might have Nusrah and four other rebel factions – but also in terms of personal and familial links,” said Sam Heller, a Beirut-based analyst studying Syrian armed groups with the Century Foundation.

On Saturday, Nusra and allied groups also appeared to ignore the agreement announced in Geneva. The jihadi group said it launched a new offensive against regime forces in southern Syria, in cooperation with another rebel front, Ahrar al-Sham, a controversial, conservative Islamist group that casts itself as a part of the rebel mainstream. For its part the Assad regime said it continued military operations “all over the country, advancing in many areas and re-establishing control on several regions,” according to the state news agency SANA.

According to Kerry, the agreement also calls for “unimpeded and sustained humanitarian access” to besieged areas in Syria, where nearly 600,000 people are trapped, according to the U.N. The largest of those areas is the eastern part of Aleppo, which is now back under siege by pro-government forces and militias. Kerry said “both sides” would be required to pull back from two key access points to the city: the Castello Road north of the city and the Ramouseh corridor to the south. Rebels, jihadists, and pro-regime groups have fought fiercely over both areas, and Kerry and Lavrov offered few specifics on how access will be enforced, leaving some humanitarian groups skeptical.

“Will this aid really change the situation? Will it enhance the humanitarian situation of people in need, or will it just be some decoration to say that, ‘yes, there is progress?” said Dr. Mohamad Katoub, a spokesman for the Syrian American Medical Society, an aid group working closely with hospitals inside Aleppo. “The lesson learned in Syria is that you cannot expect anything. You don’t know when it will be concrete and when it will be just media talks.”

Multiple foreign powers are now directly involved in the Syrian civil war, and it remains unclear what role they will play in a posible ceasefire. Along with Russia, Iran also supports the Assad regime, along with Iraqi militias and the Lebanese armed group Hezbollah. In August, Turkey also sent tanks into Syria to support rebels retaking Syrian border towns from ISIS. Excluded from any potential ceasefire, the jihadists of the Islamic State could also play a spoiler role, carrying out attacks on civilians.

Fred Hof, a former State Department Special Adviser on Syria, said in an email, “If, in the end, Russian airstrikes in Syria are subjected to an American veto and the Assad regime is kept from striking civilian neighborhoods, something of great value will have been accomplished. Nothing good can happen politically in Syria unless civilians are removed from the Assad regime and Russian bullseye. Nothing.”

“If this agreement can spare Syrian civilians from continued mass murder it will be good in and of itself,” he said.

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