Russian President Vladimir Putin has surprisingly ordered his troops to start withdrawing the “main part” of its forces in Syria from March 15.
Vladimir Putin said the Russian intervention had largely achieved its objectives.
The comments come amid fresh peace talks in Geneva aimed at resolving the five-year Syrian conflict.
Russia is a key ally of President Bashar al-Assad and his office said in a statement he had agreed to the move.
The pullout was “in accordance with the situation on the ground”, the statement said.
“I consider the mission set for the defense ministry and the armed forces on the whole has been accomplished,” Vladimir Putin said in a meeting at the Kremlin.
“I am therefore ordering the defense ministry to begin the withdrawal of the main part of our military force from the Syrian Arab Republic from tomorrow.”
Vladimir Putin said that Russia’s Hmeimim air base in Latakia province and its Mediterranean naval base at Tartus would continue to operate as normal. He said both must be protected “from land, air and sea”.
Syria’s opposition cautiously welcomed the Russian announcement.
“If there is seriousness in implementing the withdrawal, it will give the [peace] talks a positive push,” said Salim al-Muslat, spokesman for the opposition umbrella group, the High Negotiations Committee.
The US also gave a guarded response.
“We will have to see exactly what Russia’s intentions are,” said White House spokesman Josh Earnest.
Separately, US officials quoted by Reuters said Washington had received no advance warning of Vladimir Putin’s statement.
Speaking in October 2015, Vladimir Putin said Russia aimed to “stabilize the legitimate authority” of President Bashar al-Assad by intervening and “create conditions for a political compromise”.
Russia has long insisted its bombing campaign only targets terrorist groups but Western powers have complained the raids hit political opponents of President Bashar al-Assad.