President Vladimir Putin ordered the Russian military to withdraw most of its forces from Syria, timing his move to coincide with the launch of Syria peace talks Monday — an end game that allows the Russian leader to cash in on his gains and reduce his risks in the conflict.

The start of the negotiations in Geneva offers Putin an opportune moment to declare an official end to the 5½-month Russian air campaign that has allowed Syrian President Bashar al-Assad's army to win back some key ground and strengthen his positions ahead of the talks. With Russia's main goals in Syria achieved, the pullback will allow Putin to pose as a peacemaker and help ease tensions with NATO member Turkey and the Gulf monarchies vexed by Moscow's military action.

At the same time, Putin made it clear that Russia will maintain its air base and a naval facility in Syria and keep some troops there. Syria's state news agency also quoted Assad as saying that the Russian military will draw down its air force contingent but won't leave the country altogether.

The Syrian presidency said Assad and Putin spoke on the phone Monday and jointly agreed that Russia would scale back its forces in Syria. It rejected speculation that the decision reflected a rift between the allies and said the decision reflected the "successes" the two armies have achieved in fighting terrorism in Syria and restoring peace to key areas of the country.

The Syrian army said it would continue its operations against ISIS jihadists, the Nusra Front and other militant organizations "with the same tempo."

Putin: Tide has been turned

Announcing his decision in a televised meeting with Russia's foreign and defence ministries, Putin said the Russian air campaign has allowed Assad's military to "radically" turn the tide of war and helped create conditions for peace talks.

"With the tasks set before the Defence Ministry and the military largely fulfilled, I'm ordering the defence minister to start the pullout of the main part of our group of forces from Syria, beginning tomorrow," Putin said.

He also informed U.S. President Barack Obama of his move in a phone call, emphasizing the importance of U.S.-Russian co-ordination "for preserving the ceasefire, ensuring humanitarian aid deliveries to the blockaded settlements and conducting an efficient struggle against terrorist groups," according to the Kremlin, which added that the conversation was "business-like and frank."

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Russian President Vladimir Putin said his country's military would reduce its forces in Syria after achieving 'successes.' (Alexei Nikolsky/Sputnik/Kremlin/Associated Press)

Putin didn't specify how many planes and troops would be withdrawn. The number of Russian soldiers in Syria has not been revealed. U.S. estimates of the number of Russian military personnel in Syria vary from 3,000 to 6,000.

Russia has deployed more than 50 jets and helicopters to its Hemeimeem air base, in Syria's coastal province of Latakia, and they have operated at a frenetic pace, each flying several combat sorties on an average day. Russian Defence Minister Sergei Shoigu reported to Putin that thanks to the Russian air support the Syrian military has extended its control to 400 towns and villages over an area of 10,000 square kilometres.

State TV quoted Assad as saying that the collaboration between Russian and Syrian forces has secured "victories against terrorism and returned security to the country."

The UN special envoy for Syria, Staffan de Mistura, who restarted peace talks between the Syrian government and the opposition in Geneva on Monday, said he had no comment on Putin's announcement when contacted by The Associated Press.

Earlier in the day, he warned that the only alternative to the negotiations is a return to war, and described political transition in the country as "the mother of all issues."

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Russia says its fighter jets have helped the Syrian military regain control over parts of the country. (Pavel Golovkin/Associated Press)

The Russian- and U.S.-brokered ceasefire that began on Feb. 27 has largely held, but both the Syrian government and its foes have accused one another of violations. The deal with Washington has achieved a key Putin goal: raising Russia's global profile to appear as an equal to the United States in mediating the Syrian conflict that has dominated global attention.

ISIS and al-Qaeda's branch in Syria, the Nusra Front, are excluded from the ceasefire and Russia has said it would continue its fight against the groups considered terrorists by the United Nations.

A Pentagon spokesman, navy Capt. Jeff Davis, said the Russians in recent days have been pounding ISIS targets in and around the western approaches to the city of Palmyra, which is firmly under ISIS control. Davis said this has been a Russian focus since the cessation of hostilities began.

Officials said Monday they saw no immediate sign of any pullout. Although Putin's announcement caught Pentagon officials by surprise, officials have said they had questioned how long the Russian air campaign would last based on the fact that they were not making regular troop rotations.

Speaking at the United Nations, Russia's UN ambassador Vitaly Churkin did not respond to questions on whether Russian airstrikes would end.