Moscow: The first Russian planes flew out of Syria on Tuesday, at the start of a surprise withdrawal that diplomats hope will boost a new round of UN-backed peace talks.
UN peace envoy Staffan de Mistura described the Russian pullout as a "significant development" for the talks that began in Geneva on Monday.
"We hope will have a positive impact on the progress of the negotiations," he said in a statement.
A group of Su-34 bombers and a Tu-154 transport plane left Moscow's Hmeimim base in Syria headed for home, the defence ministry said, a day after President Vladimir Putin ordered most of his forces out of the war-torn nation.
Putin on Monday said Moscow's military goal had been "on the whole" completed some five-and-a-half months and 9,000 combat sorties after the Kremlin launched its bombing campaign in support of long-time ally President Bashar al-Assad.
Western leaders reacted cautiously to the announcement, with Moscow yet to specify a timeframe for the withdrawal and set to maintain its air and naval base and advanced air defence systems in Syria.
And hopes for a breakthrough at the Geneva talks remained remote, with both sides locked in a bitter dispute over Assad's future as the conflict in Syria entered its sixth year.
Pressure on Assad
As the talks entered their second day, De Mistura was expected to hold his first official meeting with the Syrian opposition High Negotiations Committee (HNC), which has repeatedly said that Assad cannot be part of Syria's political future.
But the withdrawal of the Russian troops which began airstrikes in support of the regime in September, sparking condemnation from Western powers is expected to put more pressure on Assad to negotiate during the Geneva talks.
"If the announcement of a withdrawal of Russian troops materialises, this increases the pressure on President Assad to finally negotiate in a serious way in Geneva a political transition which maintains the stability of the Syrian state and the interests of all populations," German Foreign Minister Frank-Walter Steinmeier said.
The Russian ambassador to the United Nations Vitaly Churkin also said the Kremlin's move would boost chances of a diplomatic solution to a conflict that has killed more than 270,000 people and displaced millions.
The White House said President Barack Obama had spoken to Putin following Russia's announcement, and discussed the "next steps required to fully implement the cessation of hostilities".
But US officials offered a cautious initial assessment of the Kremlin's decision.
"At this point, we are going to see how things play out over the next few days," a senior administration official said.
Ceasefire holding
Russia began its airstrikes in support of Assad's army in September, a move that helped shore up the regime's crumbling forces and allow them to go on the offensive.
Russia sent some 50 warplanes to carry out thousands of strikes across Syria arguing that it was targeting "terrorist" groups including Islamic State jihadists.
The intervention was slammed by the West and its regional allies, who insisted that Moscow was mainly bombing more moderate rebels fighting Assad.
A temporary ceasefire between Assad's forces and opponents in the country introduced on February 27 has largely held, but does not cover the IS and Al-Nusra Front groups.
Kremlin spokesman Dmitry Peskov told journalists that Moscow's Hmeimim air base and its Tartus naval facility would remain functioning and that some military contingents would stay behind.
He did not however give any details on how many soldiers would stay in Syria.
And Kremlin chief of staff Sergei Ivanov said Russia would continue to use advanced air defence systems to protect its remaining contingent in Syria.
"To effectively ensure security, including from the air, the most modern air defence technology is necessary," he was quoted by Russian agencies as saying.
'Red line'
Syria's main opposition welcomed the Kremlin's withdrawal announcement, but said it would wait and see what impact the order would have on the ground.
"We must verify the nature of this decision and its meaning," Salem al-Meslet, spokesman for the opposition HNC, told reporters in Geneva.
Despite the announcement of the withdrawal, the major sticking point at the talks in Geneva, appeared to be the fate of Assad after Damascus warned that his removal would be a "red line".
After his first official meeting with the regime on Monday, UN envoy de Mistura told reporters that "strong statements (and) rhetoric" were part of every tough negotiation and that his initial discussions with government representative Bashar al-Jaafari were "useful".
