But it's unclear whether the Russian president will be able to win over summit attendees to its anti-interference stance on Syria.
But it could all get shoved onto the back burner as leaders of the world's 20 major economic powersgather in St. Petersburg tomorrow. They meet amid gathering war clouds and an intensifying debate over who carried out the Aug. 21 poison gas attack near Damascus and what, if anything, the world community ought to do about it.
The summit will also likely spotlight the difficult personal dynamics between Vladimir Putin and Barack Obama, a problem that has become so obvious lately that both presidents have permitted themselves to publicly comment on it.
"Syria is not on the agenda, but it will be the most important topic of the summit," says Georgy Mirsky, an expert with the Center for Development and Modernization at Moscow's prestigious Institute of World Economy and International Relations.
"Everybody will be thinking about it and talking about it, at least in private. It will hang over the participants like the Sword of Damocles," he says.
In recent days Putin has laid out Russia's position on Syria in a series of statements. In a nutshell, he argues that there is no convincing evidence that the forces of Syrian strongman Bashar al-Assad launched the poison gas attack and that an exhaustive investigation should be undertaken by the United Nations to ascertain who did. Until then, the world community should undertake no action. If, after all the facts are in, a culprit has been definitively identified, then only the United Nations Security Council has the authority to decide what should happen next. If the US launches unilateral action without the UN's blessing, it will be strictly illegal, he says.
Putin repeated these views in an extensive interview Tuesday with Russia's state-run Channel One TV and the Associated Press, a performance clearly designed to make him sound moderate, reasonable, and flexible. He added the soundbite, widely picked up by world media, that he "does not exclude" military intervention in Syria if Mr. Assad's guilt is proven and the Security Council approves.
But, experts point out, Russia holds a veto in the Security Council – which it has used repeatedly over Syria – and Putin went on to explain that he rejects all the evidence that Assad's forces staged the attack so far made public, including graphic videos of the victims and US claims that itintercepted telephone calls between top Syrian officials admitting that they carried out the attack.
Speaking to the Kremlin's in-house human rights commission today, Putin was considerably more blunt.
"Congress of any country can sanction [military intervention]. But they are sanctioning aggression, because anything that is beyond the UN Security Council framework except self-defense is aggression," Putin said.
"What the US Senate is doing now is in fact legitimizing aggression, and we have all glued ourselves to TV screens and are waiting to see whether there will be a sanction or not. What we should be talking about is that this is absurd in principle," Putin said.
And, in a brief but possibly frank flash of anger, Putin appears to have called US Secretary of State John Kerry a "liar."
"I watched the debates in Congress. A congressman asks Mr. Kerry: 'Is there Al Qaeda there? There has been rumor that they are gaining strength.' He [Kerry] replies, 'No. I am telling you firmly: there are none of them there'," the independent Interfax agency quoted Putin as saying.
In fact, "the principal combative unit [acting in Syria now] is the so-called Nusra, which is an Al Qaeda unit," he said.
"And they know this. I even felt quite awkward. We are communicating with them and assume that they are decent people. And he is telling an outright lie, and he knows that he is lying. This is sad," Putin added.
A chilly relationship
Mr. Obama earlier canceled a face-to-face meeting with Putin slated for this week over the Edward Snowden affair and other irritants on a growing list of issues that have been dragging down the US-Russia relationship. He may find find it hard to bridge the growing chasm between himself and Putin.
"At the summit there will be lots of talk about Syria," says Alexei Malashenko, an expert with the Carnegie Center in Moscow.
"There are a lot of people in the world, and within the G20, who share Russia's skepticism about what happened in Syria, and there may indeed be a general anti-attack mood around. Russia can tap into that, and may indeed be planning to do that. Putin feels he has a winning issue here, at least until the attack begins. His position is rather strong," Mr. Malashenko says.
The chemistry between Putin and Obama already seems toxic. At the G8 summit in June they held a frigid sideline meeting in which neither seemed able to contain his irritation with the other. Obama subsequently described Putin's demeanor as being like "the bored kid at the back of the classroom," a remark that reportedly prompted rage in the Kremlin.
In his interview with AP, Putin put the best face on his relations with Obama.
"We work, we argue about some issues. We are human. Sometimes one of us gets vexed. But I would like to repeat once again that global mutual interests form a good basis for finding a joint solution to our problems," Putin said.
A losing issue at G20?
But if Putin thinks Obama can be made to look isolated at the G20 over the Syria crisis, he should probably think again, says Sergei Strokan, foreign affairs columnist with the Moscow pro-business daily Kommersant.
"It doesn't matter much to Obama if the UN, the pope, and Russia are all warning him not to act unilaterally in Syria. What the US decides to do is primarily a domestic issue, and nothing Putin says is likely to make much difference to him," Mr. Strokan says.
"But as for the other members of the G20, it's true that many of them have decided against participating in any military strikes against Assad. But that does not mean they support Putin's point of view. In fact, most of them are on record as agreeing with US charges that the Syrian government was behind the poison gas attack. Obama can turn this to his advantage, and find the majority will side with him, at least morally."
"Putin would be wise to keep the agenda focused on global economic issues, as was intended," Strokan adds. "In the long run, these matters are probably of more importance to most members of the G20 than whatever happens in Syria."