Russia seized the diplomatic initiative Monday with a plan for Syria to head off the threat of US military strikes by putting its chemical weapons under international control.
The move by Moscow, Syrian leader Bashar al-Assad's most powerful international ally, threatened to overshadow US President Barack Obama's push to win support for punitive action.
Russian Foreign Minister Sergei Lavrov met his Syrian counterpart Walid al-Muallem in Moscow and urged Damascus to "place the chemical weapons under international control and then have them destroyed".
"We do not know if Syria agrees to this, but if placing the chemical weapons under international control helps avoid military strikes, then we will immediately get to work on this," Lavrov said.
Muallem welcomed the Russian move, although it was not immediately clear if a still defiant Assad would give his assent.
"I carefully listened to Sergei Lavrov's statement about it," Muallem said, according to the Russian state news agency ITAR-TASS.
"In connection with this, I note that Syria welcomes the Russian initiative based on the Syrian leadership's concern about the lives of our nationals and the security of our country."
Britain's Prime Minister David Cameron expressed concern that the plan might be "a distraction tactic" but broadly welcomed the Russian initiative.
"If Syria were to put its chemical weapons beyond use, under international supervision, clearly that would be a big step forward and should be encouraged," he told lawmakers.
And UN General Secretary Ban Ki-moon, meanwhile, called for the creation of UN supervised zones in Syria where the country's chemical weapons can be destroyed.
Ban told reporters he may propose the zones to the Security Council if UN inspectors confirm banned weapons were used and to overcome the council's "embarrassing paralysis" over Syria.
"I am considering urging the Security Council to demand the immediate transfer of Syria's chemical weapons and chemical precursor stocks to places inside Syria where they can be safely stored and destroyed," he said.
There was no immediate reaction from the White House to the Russian or UN plans but US Secretary of State John Kerry had earlier argued a political solution to the conflict would be easier after military strikes.
"There is no military solution. And we have no illusions about that," he said.
"And if one party believes that it can rub out countless numbers of his own citizens with impunity using chemicals ... he will never come to a negotiating table," he said.
For his part, Assad warned Monday the United States will "pay the price" if it attacks Syria, invading Obama's home media turf with an appearance on US television.
The move pre-empted Obama's plan to give no less than six interviews to defend his strike plan to the US public and lawmakers, before giving a major national address Tuesday.
In the meantime, US cruise missile destroyers are idling in the Eastern Mediterranean, preparing for what US officials described as an extremely limited, precise punitive strike.
"You're going to pay the price if you're not wise. There are going to be repercussions," Assad told the US network CBS.
"It's an area where everything is on the brink of explosion. You have to expect everything."
His comments did not rise to the level of a precise threat, but will do nothing to calm fears that Syria and it allies Hezbollah and Iran could act to destabilize its neighbors.
A White House spokesman responded that the United States is ready for any contingency.
"The United States military is far stronger than any of Assad or his allies," said Ben Rhodes, spokesman for Obama's National Security Council.
"What we'll send is a clear message to him. He has no interest in escalating this conflict, frankly," he said.
The US Congress returned to work after its summer recess to face a barrage of classified briefings that the White House hopes will convince lawmakers to back a strike.
According to US intelligence, on August 21 a chemical attack against rebel-held suburbs of Damascus killed more than 1,400 people, including 400 children gassed in their beds.
Other outside estimates set a lower death toll, but Western capitals and the Arab League have condemned the alleged rocket barrage as a war crime and blamed it on Assad's regime.
Obama has argued an international military strike is necessary to defend the long-established international taboo against the use of such weapons.
Last week, in a surprise move, he asked US lawmakers to authorize military action, triggering a bitter debate that could forever undermine his presidential authority.
Polls show a war-weary American public opposes action against Syria and the US lower house, the House of Representatives, is led by Republicans who oppose Obama's every move.
Some liberal anti-war Democrats are also expected to oppose the motion, and the support of pro-war neo-conservatives in the Republican ranks may not be enough to push it through.
British lawmakers have already vetoed their country's involvement in strikes, and Syria's ally Russia has stymied any attempt to win UN legal backing for action.
Obama has refused to rule out acting alone, with neither congressional nor international support, but defeat at home would be a blow to his credibility and strengthen Assad's hand.
Fighting erupted in Syria in March 2011 when Assad's forces launched a brutal crackdown on a popular revolt against his rule, and soon escalated into an all-out civil war.
The UN estimates more than 100,000 have died in fighting that has seen loyalist forces and militia, backed by Lebanese Hezbollah, ranged against rebels that include Al-Qaeda allies.