President Barack Obama said Sunday the US was "not there yet" in talks with Russia about a cessation of hostilities in Syria, but that progress was possible as "around-the-clock" negotiations between US and Russian officials were underway.
"We have long been interested in finding a way to reduce the violence, improve humanitarian access on the ground, as a precursor for a political transition inside of Syria," Obama said. "It is a very complicated piece of business."
Obama pointed to "grave differences" with Russia over its support of the Syrian regime and the path forward even as US media reported a deal between Washington and Moscow could be announced as soon as later Sunday on the sidelines of the Group of 20 summit in Hangzhou, China.
CBS News reported that a deal was near that would involve military and intelligence cooperation to fight terrorist groups in exchange for Russia pressuring the regime of Bashar al-Assad, a longtime Moscow ally, to stop attacking civilians and allow humanitarian aid.
Obama said support from Russia was crucial in ending the Syrian conflict and that Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov were working to hash out "a real cessation of hostilities" to provide humanitarian relief.
"We're not there yet. And understandably, given the previous failures of cessations of hostilities to hold, we approach it with some scepticism," he said. "But it is worth trying."
Syria's conflict started with peaceful anti-government protests in March 2011.
Soon it developed into a full-blown war, with Aleppo in northern Syria bearing the brunt of the violence.
Government forces on Sunday advanced against rebels in the divided city, state media and a monitoring group reported.
Al-Assad's forces, backed by air cover from allied Russians, retook almost full control of the Armament Academy from opposition fighters in the southern part of Aleppo, the Syrian Observatory for Human Rights said.
The watchdog reported unspecified casualties.
Syria’s official news agency SANA, citing an unnamed military official, reported that the army fully controlled the academy in what the source called a “blitz operation.”
"The army units and allied forces have expanded the extent of their control in the area of military academies in southern Aleppo," the source said without details.
Last month, rebels including jihadist insurgents seized military facilities in the area from government forces in a major offensive. It allowed opposition fighters to break through government lines in southern Aleppo and link up with fighters inside the eastern rebel side of the city.
Once Syria's commercial hub, Aleppo has been divided between government forces in the west and rebels in the east since fighting erupted for control of the city in mid-2012.