Russian news agencies report that Moscow has given the United States its plan for securing Syria's chemical weapons ahead of a meeting Thursday in Geneva between U.S. Secretary of State John Kerry and his Russian counterpart.
Details were not available. Kerry has said that reaching any agreement on a chemical weapons plan would be "exceedingly difficult."
A French official said Wednesday that negotiations have begun on a proposed U.N. resolution that aims to ensure that the Russian plan is implemented quickly. Russia has already disputed key elements of such a resolution, including language allowing the use of force against Syria.
U.S. President Barack Obama, in a speech Tuesday, referred to the Russian proposal and Syria's reported agreement as "encouraging signs," but also stressed that the U.S. military would be ready to respond if diplomacy fails.
Obama has warned he could launch a "limited" military strike on the government of Syrian President Bashar al-Assad to punish it for allegedly carrying out a chemical attack in Damascus last month. Assad blames the attack on rebels.
Under a potential U.S.-Russian deal, Assad's government would surrender its chemical weapons to the United Nations to have them destroyed, and the United States would freeze its plans for military action.
Obama said he asked Congress to postpone a vote authorizing military action against Syria to let the diplomatic initiatives play out.
Iran and China, which have opposed outside military intervention in Syria, expressed optimism about the diplomatic path on Wednesday.
But, Iranian Supreme Leader Ali Khamenei, an Assad ally, also cast doubt about Western intentions.
"The latest developments, if they can be taken seriously, show that they [United States and its allies] have stepped back from the inconsiderate and mistaken actions that they had taken in the past few weeks. We hope this [turnabout] is indeed serious," said Ayatollah Khamenei .
Turkish President Abdullah Gul, whose government strongly opposes Assad, said the diplomatic efforts should focus on more than just "cleaning up" Syria's chemical weapons.
"This is not only a problem of chemical weapons. The United States should not consider this only as a matter of chemical weapons. There is a civil war in this country where more than 100,000 people have been brutally killed," said Gul.
Russian analyst Fyodor Lyukanov, editor of Russia in Global Affairs magazine, said Moscow sees Obama's decision to delay military strikes against Syria as a diplomatic victory.
"For the United States, it might be a good solution because Obama and Congress can say, 'That's because of us. We pressed, made big pressure on Assad. We threatened him with war and then he gave up.' For Russia, this is a very good opportunity to show that the Russian position did make sense," said Lyukanov.
But, Paul Schulte, a London-based chemical weapons analyst with the Carnegie Endowment, said he doubts that the Russian approach will suffice.
"The Russian plan, which might be a wild card or might be a game-changer, is still very unclear, and there is a lot of skepticism about whether it could ever work," he said.
Alexander Golts, a military analyst and editor of an online journal, said the Russian president has had bad experiences with the leaders of North Korea and Iran.
"The basic question about [the] Russian initiative is, can you trust [the] words of Syrian officials, or not? Unfortunately, Russian leader Vladimir Putin had a rather bad story with two leaders of specific countries - [the late North Korean leader] Kim Jong Il and [former Iranian president] Mahmoud Ahmadinejad. Putin met each of them, received the promises he wanted, and the next day both of these men said they were misunderstood and joking," said Golts.
Any disposal of Syria's chemical weapons also would face practical obstacles, said international security expert Joanna Kidd of London's King's College.
Syria is believed to have 1,000 tons of highly toxic agents, spread over 60 locations, in the midst a civil war that has claimed 100,000 lives and displaced one-third of the population.
"It is a job that would take several months to do. And of course, one should not forget that obviously there is a civil war that would greatly complicate the process," Kidd said.
Military analyst Golts said the best strategy might be for international peacekeepers to deploy and use mobile incinerators.
"When Russia previously faced the problem of dismantling its own chemical weapons, it preferred not to move these agents all over the country, but to build plants and special facilities for destroying these weapons directly in places where these weapons were stored," said Golts.
In another development, a U.N. commission of inquiry said it has evidence that the Assad government and one rebel group have committed at least eight massacres over the past year and a half. The commission released its latest report on the human rights situation in Syria on Wednesday.
The U.N. investigators accused both the Syrian government and opposition forces, including Islamist foreign fighters, of war crimes. They said the Syrian government, however, has committed the vast majority of killings and other abuses.
Peter Bouckaert, emergencies director for the New York-based group Human Rights Watch,said he finds the U.N. report disturbing.
"It shows that the violations being committed in Syria continue at the same intensity, if not greater intensity as before," said Bouckaert.
"The levels of massacres, summary executions, indiscriminate bombings of towns [is a concern], as well as a significant increase of abuses being committed by opposition forces, particularly some of the more extreme elements, such as the jihadi groups of [al-Qaida's] Islamic State of Iraq [and the Levant]."
Reporting by James Brooke in Moscow, Al Pessin in London, Lisa Schlein in Geneva, and Jeff Seldin and Michael Lipin in Washington.