Syrian President Bashar al-Assad has accepted a ceasefire deal agreed by Russia and the United States that is set to begin later this week, the state-run SANA news agency reported Tuesday.
The agreement, which does not apply to Islamic State and other UN-designated terrorist groups, would begin at midnight local time Saturday (2200 GMT Friday), according to the State Department.
Al-Assad also excluded "terrorist" groups, including the al-Qaeda linked al-Nusra Front, saying they are not parties.
The Syrian opposition has been more cautious. The Higher Negotiations Committee of rebel and opposition groups said its agreement is conditional on there being international guarantees that Russian and Iranian forces will respect the truce.
The opposition also demanded the implementation of humanitarian measures including an end to sieges, artillery shelling and air raids.
As part of the agreement between Moscow, which backs al-Assad, and Washington, which believes the Syrian president has lost the legitimacy to rule, the warring factions must indicate their willingness to abide by the ceasefire agreement by noon Friday.
The US acknowledged implementation will be difficult. "We know that there are a lot of obstacles, and there are sure to be some setbacks," White House spokesman Josh Earnest said.