Russia and the US have announced an agreement on Syria starting with a “cessation of hostilities” from sunset on Monday.
Under the plan, the Syrian government will end combat missions in specified areas held by the opposition.
Russia and the US will establish a joint centre to combat jihadist groups, including so-called Islamic State (IS).
The announcement follows talks between US Secretary of State John Kerry and his Russian counterpart, Sergei Lavrov.
The plan would need both the regime and opposition “to meet their obligations”, Mr Kerry said in Geneva.
The opposition had indicated it was prepared to comply with the plan, he said, provided the Syrian government “shows it is serious”.
Mr Lavrov said Russia had informed the Syrian government about the arrangements and the Syrian government was “ready to fulfil them”.
The accord also provides for humanitarian access.
“The cessation of hostilities requires access to all besieged and hard-to-reach areas, including Aleppo,” Mr Kerry said.