Russian President Vladimir Putin ordered a partial pullout of the Russian military from Syria on Monday, after saying his troops largely achieved their combat goals in the country.

He also ordered the country’s diplomatic efforts be stepped up to secure a peace deal in Syria. The move was announced on the day U.N.-backed peace talks on Syria resumed in Geneva.

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

"With the tasks set before the Defense Ministry and the military largely fulfilled, I'm ordering the Defense Minister to start the pullout of the main part of our group of forces in Syria, beginning tomorrow," he said.

Putin didn't specify how many planes and troops should be withdrawn. He emphasized that the Russian airbase in Hemeimeem in Syria's coastal province of Latakia and a naval facility in the Syrian port of Tartous will continue to operate.

The number of Russian soldiers in Syria has not been revealed.

The U.N. 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.

Countries in U.S. Coalition and Islamic Military Alliance | InsideGov

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."

As peace talks opened in Geneva, President Obama spoke with President Vladimir Putin about the withdrawal and discussed "next steps" in upholding the fragile truce that has quieted the country's civil war, the White House said.

In a statement about the phone call, the White House said Obama told Putin he welcomed the "much-needed reduction in violence" since the ceasefire took effect late last month. But the president also noted the Syrian regime's continued "offensive actions" threaten to break the deal and could undermine plans for a United Nations-led political process.

"The President underscored that a political transition is required to end the violence in Syria," the White House said.

The two leaders spoke shortly after Putin announced the partial withdrawal. For nearly six months, Russia has mounted an air campaign backing up the Syrian President Bashar Assad's battle against opposition forces. The White House statement did not offer the president's reaction to Putin's move and instead focused on what else Russians could do to use its influence with the Assad regime.

The White House said Obama noted "some progress" on getting humanitarian aid to Syrians, but added that regime forces continue to impede access to some areas, particularly Daraya.

U.S. officials told Reuters they had no advanced warning of Putin's decision to withdraw the main part of Russian forces from Syria, nor had they seen any indications of preparations for such a withdrawal.  

From Fox News