MOSCOW: Russian warplanes and troops stationed at Russia's air base in Syria started leaving for home on Tuesday after a partial pullout order from President Vladimir Putin the previous day, a step that raises hopes for progress at the newly reconvened UN-brokered peace talks in Geneva.

The UN special envoy for Syria called Putin's announcement a "significant development." Staffan de Mistura said in a statement that his team hoped the Russian drawdown would have a "positive impact" on the negotiations aimed at finding a political solution to Syria's war and "a peaceful political transition in the country."

Putin announced the withdrawal of most of the Russian forces from Syria on Monday, just hours after de Mistura had reconvened indirect peace talks between representatives of Syrian President Bashar Assad's government and those of the so-called moderate opposition. After meeting with a government delegation on Monday, the U.N. envoy was to meet with opposition representatives on Tuesday.

Later Tuesday, Putin's spokesman Dmitry Peskov denied that Russia's decision was prompted by Kremlin's displeasure with the Syrian government's tough position in the negotiations — or that it was intended to put pressure on Assad.

Iranian Foreign Minister Mohammad Javad Zarif Zarif welcomed Russia's decision to begin withdrawing forces from Syria, saying it indicated that Moscow doesn't see an imminent need to use force for maintaining the cease-fire, which is fragile but holding.

"That in and of itself should be a positive sign. Now we have to wait and see," Zarif said during a visit to Australia.

Russia's Defense Ministry said a group of Su-34 bombers was the first to depart on Tuesday, 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 kilometres (3,100 miles) away from the Syria base, the ministry said.

Russian state television showed video of the three warplanes taking off and flying in formation behind a larger transport aircraft, and also reported that two more groups had subsequently set off for home. A later report showed the Su-34 pilots receiving a hero's welcome at an air base near the Russian city Voronezh.

Putin didn't specify how many aircraft and troops would be withdrawn.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 US estimates of the number of Russian military personnel vary from 3,000 to 6,000.

Russia had deployed more than 50 jets and helicopters to its Hemeimeem air base, in Syria's coastal province of Latakia. The number of sorties had been drastically reduced since the cease-fire went into effect on Feb. 27.

Meanwhile, a Russian deputy defence minister said Russia would continue striking Islamic State militants and Syria's al-Qaida branch, known as the Nusra Front, as well as other militant factions that the UN Security Council has designated as terrorist organizations. The Syrian army has said it also would continue its operations against these groups "with the same tempo."

While the Russian air campaign had brought positive results, it was too early to speak about victory over terrorism and the Russian forces remaining in Syria "have the task of continuing to strike terrorist targets," Nikolai Pankov said during a ceremony at the Syria base honoring the departing Russian pilots.

The head of the defence 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 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.