As the first Russian servicemen headed home from Syria on Tuesday, Moscow said it planned to keep at least 800 in the country to man its airbase and naval facility there.
"These bases need to be protected. This requires a minimum of two battalions, about 800 people," the head of the upper house of parliament's defence committee, Viktor Ozerov, told the Interfax news agency.
"We also retain the right to conduct aerial reconnaissance, so some of the planes and flight teams will also stay," Ozerov said. He added that Russia could also maintain S-400 missile systems in Syria for additional defence.
Russia has an airbase in the Syrian province of Latakia and a naval facility in the province of Tartus. Both are on the Mediterranean coast.
Russian President Vladimir Putin declared on Monday that the military would begin withdrawing the majority of its forces from Syria because their task had been "completely fulfilled."
Putin's spokesman, Dmitry Peskov, said Tuesday that Putin had made the decision unilaterally without discussing it with other world leaders involved in the conflict, state news agency TASS reported.
The Kremlin said in a statement, however, that Putin had the consent of Syrian President Bashar al-Assad, a longtime ally, to begin withdrawing the troops as a recently instated ceasefire in the country was predominantly holding.
"Russia's biggest risk in the Syria operation was to be dragged into a long-term military conflict. As we see, that did not happen," prominent Russian political analyst Yevgeny Minchenko told Interfax.
"The Russian military demonstrated well enough its diverse capabilities," Minchenko said.
The first group of Russian planes, including a Tu-154 airliner and Su-34 bombers, departed from Russia's Humaymim airbase in Latakia on Tuesday to travel more than 5,000 kilometres back to a home base in Russia, the Defence Ministry said on its website.
Russia began a bombing campaign against rebels in Syria in September to support al-Assad's regime in an effort to maintain some stability in the country, divided in a civil war that is now dragging into its sixth year.
Some Western and regional powers have supported rebel groups in the conflict on the accusation that al-Assad's regime has committed crimes against humanity, including mass killings of civilians.
The United Nations' envoy to Syria, Staffan de Mistura, welcomed Russia's withdrawal of troops and said he hoped it will have a positive impact on peace talks between al-Assad's government and the Syrian opposition.
A new round of the peace talks, brokered by De Mistura, started Monday in Geneva.