US Secretary of State John Kerry Tuesday held high stakes talks in the Russian resort of Sochi to press President Vladimir Putin to fully implement a shaky Ukraine ceasefire and urge renewed efforts to end the Syrian war.
On the highest-level US visit to Russia since the conflict in Ukraine erupted, Kerry first met with his Russian counterpart Sergei Lavrov in talks that were stretching to more than four hours, ahead of his highly-anticipated talks with Putin.
At "a critical moment" for Ukraine, Washington was looking to ensure the "next steps in concrete implementation" of the truce deal, as well as to "see whether they (Russia) see an opportunity to do more together" in Syria, a senior State Department official said.
Kerry would also discuss Yemen and Libya and brief Putin on the negotiations on curtailing Iran's nuclear programme, with talks to resume Wednesday in Vienna.
After top US officials snubbed Putin's huge military victory parade on Sunday, Kerry and Lavrov shared a poignant moment when, watched by dozens of schoolchildren, they laid wreaths at a World War II memorial to mark 70 years since the defeat of Nazi Germany.
Ties between Moscow and Washington collapsed when Russia seized the southern Ukrainian peninsula of Crimea in early 2014 and buttressed separatists in eastern Ukraine.
But after a year of tensions, signs are emerging that both Russia and the West may be ready to seek detente.
"We have a lot of business we could do together if there is interest," the senior State Department official told reporters travelling on Kerry's plane.
"It's important for us to keep these lines of communication open."
Kremlin spokesman Dmitry Peskov described the visit by Kerry as "extremely positive" and said the talks would cover a wide range of topics including international "hot-button issues".
"Through dialogue we can search for a path towards some sort of normalization of ties and closer coordination in solving international problems," Peskov was quoted as saying by Russian wires.
Putin has refused to budge on Ukraine, despite a ceasefire agreement re-negotiated in February in Minsk, but has signaled readiness to mend ties with Washington and Brussels as Russia chafes under biting Western sanctions.
"We have been very, very clear publicly that if Minsk is fully implemented… including restoration of the sovereign border, there will be an opportunity to roll back sanctions," the US official said.
But "we've also made clear that if there is more serious violations that the pressure will increase."
Russia's opposition on Tuesday released a report based on research by slain Putin critic Boris Nemtsov detailing allegations of widespread Russian army involvement in Ukraine that Moscow has denied.
Kerry's visit also comes hot on the heels of German Chancellor Angela Merkel, who has led European efforts to broker a peace deal in Ukraine and who said in Moscow on Sunday that there was still no genuine ceasefire.
Kiev and the pro-Russian rebels accuse each other of continuing to violate the truce despite claims of withdrawing heavy weapons from the frontline.
The crisis in Ukraine is also likely to top the agenda at NATO foreign ministers talks on Wednesday in Antalya, Turkey, Kerry's next destination after his meetings in Sochi.
While Kerry has met many times with Lavrov in various European cities, he has for some time been anxious to hold face-to-face talks with Putin, who US officials dubbed the "main decision-maker."
The two men last met in Moscow in May 2013.
"There is a question now whether this might not be a better moment, I think we'll see how things go," the official told reporters.
Kerry also plans to update Putin on his recent talks in New York with Iranian Foreign Minister Mohammad Javad Zarif as the clock ticks down to a June 30 deadline for a final deal to stop Iran acquiring nuclear weapons, and would stress the need to stay in lockstep.
He would likely raise the issue of Russia's lifting of a ban on selling sophisticated S-300 air defense missile systems to Tehran.
On Syria, where the war is now in its fifth year, American officials believe the tide may be turning against President Bashar al-Assad, and hope to gauge Putin's feelings on his long-time staunch ally.
Kerry would also highlight the use of chlorine gas by the Assad regime. Washington wants the UN Security Council to probe reported chlorine gas attacks.
AFP contributed to this report.