WASHINGTON (AFP) - US Secretary of State John Kerry made an impassioned plea to the Syrian regime to seize the moment on Tuesday to try to make peace and help destroy its chemical weapons.
As Russia floated proposals to secure Syria's chemical arms stock, Mr Kerry was set to dash to Geneva on Thursday for hasty talks with his Russian counterpart Sergei Lavrov.
A US official confirmed to AFP that Mr Kerry was heading back to Europe only days after returning from a whirlwind trip which took in Lithuania, France and Britain.
The trip was apparently hatched during Tuesday telephone talks between Lavrov and Kerry - which came only hours before President Barack Obama is due to address the nation.
Mr Kerry, who has been leading the Obama administration's charge for military strikes against the Syrian regime, said he expected Russia would send details of its proposals to the United States late Tuesday.
In another day of fast-moving diplomatic drama, Syrian Foreign Minister Walid al-Muallem said Damascus, which has been battling a two-year rebellion, wanted to join the international treaty banning chemical weapons.
Directly addressing Muallem and President Bashar al-Assad, Mr Kerry said he hoped the two men "would take advantage of this opportunity as a moment to try to make peace in Syria."
"Help us in the next days, working with Russia, to work out the formula by which those weapons can be transferred to international control and destroyed," Mr Kerry pleaded during an online discussion hosted by Google.
But Mr Kerry also insisted that any move to neutralise Syria's chemical weapons must have teeth, and lay out "consequences" if it turns out to be a delaying tactic to avoid US military action.
Mr Assad's regime is accused of using chemical weapons in an August attack near Damascus, which Washington says killed 1,400 people.
Videos of adults and children writhing in agony have galvanised global outrage, marking a new phase in the dragging civil war which has killed some 100,000 people, according to the United Nations.
"If we can in fact secure all of the chemical weapons in Syria, through this method, clearly that's by far the most preferable, and would be a very significant achievement," Mr Kerry said.
He stressed the proposals must be an "ongoing verifiable process" with full international access to all of the sites in question. "This cannot be a game.
And that we have made very, very clear to the Russians," he said.
Since the idea was first floated on Monday, it has garnered growing global support and the United States, France and Britain are now working on a resolution to go before the United Nations.
"We need a full resolution from the Security Council in order to have the confidence that this has the force that it ought to have," Kerry said.
"Common sense tells us that we don't want to buy into something that isn't going to get the job done. So this has to be transparent, accountable, fully implementable and a clearly verifiable process and we're going to have to work at how that's going to be achieved," he said.
"But it's also going to have consequences if games are played or somebody tries to undermine this." At an earlier Congress hearing, Defence Secretary Chuck Hagel said while everyone was hopeful the move could be "a real solution to the crisis" the threat of "credible, real" US military action had to remain on the table.
Mr Kerry told lawmakers Syria had about "1,000 metric tonnes of numerous chemical agents including sulfur, mustard gas and binary components for sarin gas and VX." US experts were already working on how to implement the "exceedingly difficult" task of securing and destroying the weapons, he told the House Armed Services Committee.
Mr Obama will address the nation later on Tuesday as he seeks to build support for limited US military strikes, and Mr Kerry warned Washington would not "wait too long" for the Russian proposal.
Mr Hagel added: "We must be very clear-eyed and ensure that it is not a stalling tactic by Syria and its Russian patrons.
"The threat of a US military action, the credible, real threat of US military action, must continue."