MOSCOW -- Russia's defense ministry said Tuesday that the first group of warplanes stationed at the Russian air base in Syria has left for home following a pullout order from President Vladimir Putin.
The development came as U.N.-brokered Syria peace talks between Syrian President Bashar Assad's government and the opposition were to resume for a second day in Geneva.
Putin announced the withdrawal of most of the Russian forces from Syria on Monday night, timing his move to coincide with the resumption of the talks in Geneva.
The Defense Ministry said the first group of warplanes to depart included an unspecified number of Su-34 fighter jets, accompanied by a military transport aircraft. The planes would be making stops at airfields in Russia for refueling and technical checks since some of them are stationed more than 5,000 kilometers (3,100 miles) away from the Syria base, the ministry said.
Putin didn't specify how many aircraft and troops would be withdrawn. Russia has not revealed how many soldiers it has deployed to Syria, where it maintains a naval facility as well as an air base, but U.S. estimates of the number of Russian military personnel 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.
The head of the defense committee in Russia's upper house of parliament, Viktor Ozerov, said Tuesday that he estimated about 1,000 Russian military personnel would remain in Syria at the two bases, the Interfax news agency reported.
Ozerov said Russia would need a minimum of two battalions, a total of 800 troops, to protect the two bases. In addition, Russia would continue to conduct air reconnaissance, requiring some of the plane crews to remain, and the military specialists advising the Syrian army also would stay, he said.
He said Russia would keep its long-range S-400 air defense missiles at the base. Russia deployed the powerful system in November after Turkey downed a Russian jet along the Syrian border.
The start of the negotiations in Switzerland on Monday offered Putin an opportune moment to declare an official end to the five-and-a-half-month Russian air campaign, which has allowed Assad's army to win back some key ground and strengthen his positions ahead of the talks.
Announcing his decision in a televised meeting with Russia's foreign and defense ministers, Putin said Monday that the Russian air campaign has allowed Assad's military to "radically" turn the tide of war and helped create conditions for peace 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 the Islamic State group, al-Qaida's Syria branch known as the Nusra Front and other militant factions in Syria that have been designated as terrorist groups by the United Nations "with the same tempo."
Associated Press Writer Lynn Berry in Moscow contributed to this report.