US Secretary of State John Kerry arrived in Moscow on Wednesday seeking to gauge whether Vladimir Putin is ready to discuss ways to ease Bashar al-Assad from power in Syria.

American officials see movement on Assad's future as key to giving momentum to the peace talks being led by UN envoy Staffan de Mistura in Geneva to end Syria's civil war.

Moscow agreed to bring its ally's representatives to the table for talks with rebel delegates, but the Russian president insists that only Syrian voters can decide Assad's fate.

Any UN-backed elections would be at least 18 months away -- even if the talks go well -- and, without guarantees of Assad's exit, Syrian opposition leaders may yet baulk.

So Kerry touched down outside Moscow hoping for a sign that Russia -- which has just withdrawn some of the forces it sent to shore up Assad's regime -- may be more flexible.

"What we're looking for, and what we've been looking for for a long time is how are we going to transition away from Assad's leadership," a senior US official told reporters.

Kerry is in regular contact with his Russian counterpart Sergei Lavrov, but the top US diplomat knows any change in the Kremlin's posture will only come from Putin himself.

"On the Russian side, there's only one decision maker and you need to be in the room with him to evaluate what's possible," the State Department official said.

- An opening for change? -

The official said a shaky ceasefire between regime and rebel forces and Russia's partial withdrawal could mark an opening for Putin to shift his stance on Assad.

"The question is whether we can get down to brass tacks with the Russians on how to get from here to there in terms of transitioning the government," the official said.

But the American delegation is cautious about predicting a breakthrough, insisting the visit is as much about judging Putin's true stance as convincing him to change it.

Kerry is to meet both Lavrov and Putin on Thursday at the Kremlin. Later on Wednesday he was to meet in Moscow with German Foreign Minister Frank-Walter Steinmeier.

Aside from Syria's five-year civil war, Kerry and his hosts were also to address the crisis in Ukraine.

Kerry is to give his support to German and French efforts to convince Putin to rein in pro-Russian separatist rebels and allow the full application of the 2014 Minsk Protocol.

Under this plan, Kiev will accord the breakaway region a measure of autonomy and hold elections while Russia should end support for the rebels and respect Ukraine's border.

Russian general admits special forces 'directing warplanes' in Syria
Moscow (AFP) March 23, 2016 - Russia's elite special forces contingents are active on the battlefield in Syria, directing Russian warplanes, the commander of Russia's forces in Syria admitted in an interview published Wednesday.

"I won't conceal that there are also contingents of our special operations forces in Syria," said Alexander Dvornikov, who serves as commander of Russian troops in Syria and recently received top military honours from President Vladimir Putin.

"They are carrying out additional reconnaissance of targets for Russian airstrikes, they direct aircraft to targets in far-flung areas and solve other special tasks," he said in an interview to Rossiyskaya Gazeta state newspaper.

Moscow has said it has advisors active in Syria but Dvornikov made it clear the special forces officers were a separate group, while advisors trained both the Syrian army and other groups fighting alongside with regime forces, including the Syrian Kurds.

"Our military advisors worked and are working on all levels, including tactical," he said.

Within a short time of launching the campaign on September 30, Russia "created a system of military advisors", he said. "They successfully solved the issue concerning training of government forces, Kurds and other patriotic groups," said Dvornikov.

Russia also delivered a whole array of equipment to the Syrian army, including "artillery systems, communication and surveillance equipment", he said.

Dvornikov said he first arrived with his group to Syria in September, when "the situation was definitely not in favour of Damascus" as "militants" had controlled most of Homs, were on the offensive in Latakia and were preparing to take Aleppo.

Russian forces have "radically changed the situation" in five and a half months, he said.

With Syrian forces on the offensive, the taking of Palmyra under government control would "cut (Islamic State group) into two parts and open the road toward Raqa and Deir El Zor, creating conditions for reaching the border to Iraq and taking it under control," he said.

"The possible breakup of the country has been prevented," he said.

Russia's Putin ordered a surprise withdrawal of the main part of Russia's forces in Syria last week, and arrival of several warplanes back to Russia was a highly publicised affair, with pilots hailed as victorious heroes and broadcast live.

However it was clear that many Russian officers will remain in Syria. Dvornikov said that the remaining contingent will have to ensure the enforcement of current ceasefire and security of its bases in Tartus and Hmeimim.