By Dmitry Solovyov, Tom Perry and Suleiman Al-Khalidi
Russian warplanes have flown home from Syria as Moscow starts to withdraw forces that have tipped the war President Bashar al-Assad's way.
Russian television showed the first group of Su-34 jets landing from Syria at a base in the south of the country.
The pilots were greeted by 200-300 servicemen, journalists, and their wives and daughters, waving Russian flags, balloons in red, white and blue, and flowers.
They were mobbed and thrown in the air by the crowd. A brass band played Soviet military songs and the national anthem. Two priests paraded a religious icon.
As the first aircraft touched down in Russia, UN envoy Staffan de Mistura called President Vladimir Putin's surprise move a "significant development" towards resolving a conflict which this week passes its fifth anniversary.
Assad's opponents hope Putin's announcement on Monday that most Russian forces would be withdrawn signalled a shift in his support. However, its full significance is not yet clear: Russia is keeping an air base and undeclared number of forces in Syria.
Russian jets were in action against Islamic State on Tuesday. Assad also still enjoys military backing from Iran, which has sent forces to Syria along with Lebanon's Hezbollah.
Heavy Russian air support was reported helping the Syrian army make major gains against IS near the ancient city of Palmyra..
At least 26 people were killed east of the IS-held city on Tuesday, the British-based Syrian Observatory for Human Rights reported.
Russia said last month Assad was out of step with its diplomacy, prompting speculation Putin is pushing him to be more flexible at the Geneva talks, where his government has ruled out discussion of the presidency or a negotiated transfer of power.
Damascus has dismissed any talk of differences with its ally and says the planned withdrawal was co-ordinated and the result of army gains on the ground.
British Foreign Secretary Philip Hammond, whose government supports the opposition, indicated the gaps in Western understanding of Putin, saying he had "no insight at all into Russia's strategy" after a decision that came out of the blue.
The West had been equally surprised by Putin's decision to intervene. "Unfortunately none of us knows what the intent of Mr Putin is when he carries out any action, which is why he is a very difficult partner in any situation like this," Hammond said.
Analysts in Moscow said Putin's acquisition of a seat at the diplomatic top table may have motivated his move to scale back his costly Syria campaign.
Russia appeared to be following through on its pledge, the US White House said, but spokesman Josh Earnest said it was too early to assess the broader implications, adding Moscow did not give the US direct notice of its withdrawal plan.
US Secretary of State John Kerry welcomed Putin's announcement and said he planned to visit Moscow next week for what he called the best opportunity in years to end the war.
US-Russian co-operation has already brought about a lull in the war via a "cessation of hostilities agreement", though many violations have been reported.