The United States and Russia hailed a breakthrough deal on Saturday to put Syria's peace process back on track, including a nationwide ceasefire effective from sundown on Monday.
"Today, Sergei Lavrov and I, on behalf of our president and our countries call on every Syrian stakeholder to support the plan that the United States and Russia have reached, to ... bring this catastrophic conflict to the quickest possible end through a political process," US Secretary of State John Kerry said.
Russian Foreign Minister Sergei Lavrov said that despite continuing mistrust, the two sides had developed five documents that would enable coordination of the fight against armed groups and a revival of Syria's failed truce in an enhanced form.
"This all creates the necessary conditions for resumption of the political process which has been stalling for a long time," Lavrov told a news conference.
READ MORE: Kerry and Lavrov holding talks on Syria ceasefire deal
Al Jazeera's Jonah Hull, reporting from Geneva, said that the US and Russia have been trying hard in recent months to hammer out a ceasefire deal and pave the way for UN-sponsored peace talks to restart in Geneva.
"On Thursday, it did not even look like Kerry was coming to Geneva at all. The State Department said that the two sides were not close enough to warrant a meeting. It is not clear what changed after that," he said.
Washington wanted concrete steps from Russia to force its Syrian ally President Bashar al-Assad to stop his aerial campaign and to lift the siege of Aleppo, a key city near the Turkish border.
"We need to see a situation where it is clear within whatever is being agreed with the Russians that there will not be a siege of Aleppo," a senior US official quoted by the AFP news agency told reporters.
Pro-government forces have recently taken back a strategically important district on Aleppo's southern outskirts, rolling back nearly every gain from a major month-long rebel offensive there, the Syrian Observatory for Human Rights said.
The government advance further seals off Aleppo's opposition-held eastern districts and government troops backed by the Russian air force have completely encircled opposition-held neighbourhoods.
The conflict has so far claimed an estimated 400,000 lives, according to the UN special envoy for the Syria crisis Staffan de Mistura. Millions of others have been displaced during the five years of war.
Source: Al Jazeera News And Agencies