Beirut/Cilvegozu (Turkey): The United States and Russia said on Friday they wanted to extend the four-day-old ceasefire in Syria they have co-sponsored, although the agreement looked increasingly shaky, undermined by sporadic violence and a failure to deliver aid.
The second attempt this year by the Cold War-era superpower foes to halt the conflict has succeeded so far in curtailing violence, but it remains a risky gamble in a war that has made a mockery of all previous peace efforts.
Washington and Moscow, which support opposite sides in the conflict between President Bashar Al Assad and rebels trying to unseat him, have agreed to share targeting information against militant fighters that are their common enemies, if the truce holds.
Although the details of the pact remain secret, that could see them wage war on the same side for the first time since World War Two. But such unprecedented cooperation would come at a time of deep mistrust between the Cold War era-foes, when relations between them are at their worst for decades.
On the ground, the ceasefire has been reluctantly accepted by rebels who call it skewed in favour of Assad but say they have no choice because of the desperate humanitarian condition of civilians in besieged areas.
Assad's government, which holds its strongest position on the battlefield since the early days of the war, also is in no hurry to compromise.
Moscow, which holds the key to delivering the cooperation of its ally Assad, said it was ready to extend the truce by 72 hours and called on Washington to press rebels to abide by it.
Washington said it agreed that an extension was important, but also voiced alarm over the failure of aid to arrive.
Secretary of State John Kerry, who personally hammered out the agreement despite scepticism among some US administration colleagues, told Russian Foreign Minister Sergei Lavrov that Washington would not start the agreed joint targeting of militants until aid begins to flow.
The main dispute of the truce so far is over aid to Aleppo, Syria's biggest city before the war, divided between rebel and government-held zones for years. Pro-government forces encircled the rebel zone this month, trapping an estimated 300,000 civilians there with no way to bring in food.
The United Nations has pointed the finger at the government for holding up aid, saying it asked for permission to reach all besieged areas and was denied letters guaranteeing access.
"In order to actually initiate the actual movement of these convoys we need the facilitation letters. They have not come," UN humanitarian affairs spokesman Jens Laerke said in Geneva. "It's highly frustrating."
Both sides accuse each other of violating the truce and failing to withdraw from the road that would be used to deliver aid to Aleppo. Moscow said on Friday the Syrian army had withdrawn from the Castello Road but returned its troops there after they came under fire from rebels.
Insurgent groups in Aleppo said they had seen no such withdrawal from the government side, and would not pull back from their own positions around the road until it did so.
"The regime has not withdrawn from the area," Zakaria Malahifji of the Aleppo-based Fastaqim rebel group told Reuters on Friday.
Two aid convoys destined for Aleppo were still stuck on the Turkish border after several days while the sides argued over how the supplies were to be delivered. The trucks contain flour for more than 150,000 people and food rations for 35,000 people for a month, a UN spokesman said.
Humanitarian access hinges on control of the Castello Road, the main route into the besieged rebel-held part and a major frontline in the war, but so far there has been no progress towards opening it.
"By today (Friday) this morning nothing had happened on the Castello Road ... There is nothing new in Aleppo," Malahifji earlier told Reuters by phone.
Moscow is still talking up the agreement. Kremlin spokesman Dmitry Peskov told reporters on a conference call: "In general, we can still state that the process is moving forward, despite some setbacks."
But a Russian defence ministry official said the situation in Syria "could get out of control" unless Washington forces the rebels to comply with the ceasefire.
"We expect decisive measures from the American side, aimed at influencing the armed groups under their control to rigorously carry out the September 9 agreement," Lieutenant-General Viktor Poznikhir said.
After three days which saw a marked decrease in violence and no deaths, the first civilians since the start of the truce were killed on Thursday, according to the Syrian Observatory for Human Rights, a monitoring body. Three more died and 13 were injured in air strikes in rebel-held Idlib province on Friday, the Observatory said. A number of shells were also fired by insurgents into two besieged villages.
Clashes hit areas east of Damascus on Friday. Residents in the city centre were woken up by a large explosion, a witness said, and shells fell near its eastern limits.
The Britain-based Observatory said the violence stemmed from clashes between rebels and government forces in the Jobar district on Damascus's eastern outskirts. Each side said the other had attacked first.
The United States and Russia will brief United Nations Security Council members on the deal behind closed doors on Friday, diplomats said. Russia is pushing for the Security Council to adopt a draft resolution next week endorsing the deal.
Assad appears as uncompromising as ever. He vowed again this week to win back the entire country, which has been splintered into areas controlled by the state, a constellation of rebel factions, IS militants and Kurdish militia fighters.
In a separate development east of Aleppo, a small number of US military personnel entered the rebel-held town of Al Rai near the Turkish border as part of operations to coordinate air strikes against IS, a senior rebel source said.
The Americans were forced to leave the area after Turkish-backed rebels protested against their presence, the source said.
One US official, speaking on condition of anonymity, said initial reports appeared to confirm the incident involving a small group of US forces.
The Pentagon did not immediately respond to requests for comment on the incident, but it acknowledged that US special operations forces are accompanying Turkish and Syrian opposition forces battling IS in and around the area of the Syrian border near Jarabulus and Al Rai.