Is Russia's proposal for international monitors to oversee Syria's arsenal of chemical weapons, serious diplomacy or just making trouble?
Late-night talks between the Prime Minister and Russian President were unproductive as the leaders disagree fundamentally about Syria.
President Putin is famous for his macho photo stunts and steely demeanour, but on a recent trip to an aquarium he showed a lighter side.
President Vladimir Putin's diplomacy has been much admired here in Moscow, and elsewhere as well.
He faced an apparently reluctant American president, and has given him a way out with his offer yesterday - an offer which the Americans appear to have accepted with both hands.
Then suddenly today, came the conditions: That the US must renounce the use of force.
In other words, don't go to the UN and try to get a Security Council resolution that says that force can be used if the Syrian's don't hand over their chemical weapons.
What Putin has done is to get a president who was beating the drum for war on the basis that there was no alternative, to accept now that there is an alternative.
But can President Obama now go back and pick up the rhythm of those war drums again?
Russian President Putin hinted that his country may approve a UN military operation in Syria, should further evidence of Assad's involvement be presented. However this more nuanced stance belies his ongoing links to the Assad regime, which Russia provides military and logistical support to.
Speaking from Damascus, International Editor Bill Neely looks ahead to tomorrow's G20 Summit, which may turn into a bitter affair.
The Russian foreign ministry said its expert findings show that the chemical weapon used in the chemical attack in Syria are similar to ones made by a rebel group.
President Obama said he was "always hopeful" that Russian President Vladimir Putin would change his position on Syria.
Russian President Vladimir Putin said the US Congress had no right to approve the use of force against Syria without a decision from the UN Security Council, and that doing so would be an "act of aggression".
Responding to the Russian President's comments, David Cameron's official spokesman told a regular Westminster media briefing:
If members of the international community are willing to play their full part in shouldering their responsibilities, that would be welcome. We continue to engage with all G8 and G20 partners.
Asked if Downing Street believes the president's remarks indicate a greater willingness to contemplate approving action against Assad by the UN Security Council, the spokesman said:
From the reports I have seen today, we clearly remain in very, very different places around the responsibility for the chemical weapon attacks.
We are in very different places, but we will continue to engage with all our partners. We have been working with international partners, including Russia, for some time.
Russia is sending a missile cruiser to the eastern Mediterranean to take over the navy's operations in the region, military sources said according to the Interfax news agency.
President Vladimir Putin said Russia had provided some components of the S-300 air defence missile system to Syria but had frozen further shipments.
He suggested that Russia may sell the missile systems elsewhere if western nations attack Syria without UN Security Council backing.
In an interview with The Associated Press and Russia's state Channel 1 television, he said: "We have a contract for the delivery of the S-300s. We have supplied some of the components, but the delivery hasn't been completed. We have suspended it for now.
"But if we see that steps are taken that violate the existing international norms, we shall think how we should act in the future, in particular regarding supplies of such sensitive weapons to certain regions of the world."
President Vladimir Putin has suggested that videos purporting to show children killed in an alleged chemical attack may not be reliable.
He said "there is an opinion" that the videos were a "compilation by al-Qaeda-connected bandits," the Russian Interfax news agency reports.