The US and Francepushed for a tough United Nations resolution to ensure Syrian President Bashar Assad's regime turns over its chemical weapons stockpile, but Assad's ally Russia demanded the West take the threat of force off the table if Damascus fails to meet its promises.
The diplomatic split threatened a deal that would avert American strikes against Syria.
Assad's government promised to cooperate fully with the Russian plan, which calls for Syria to put its chemical weapons under international control, for eventual destruction.
Foreign Minister Walid al-Moallem told Lebanon's Al-Mayadeen TV that Syria would place its chemical weapons locations in the hands of representatives of Russia, "other countries" and the United Nations. He promised that his country would also declare the chemical arsenal it long denied having, stop producing such weapons and sign conventions against them.
Wary that Damascus is only seeking to avoid US military action, Washington and France said they seek strong UN language to enforce the Russian plan. France said it would put forward a draft resolution under Chapter 7 of the UN charter, making it enforceable with military action.
That met swift opposition from Russia.
President Vladimir Putin said the plan can only work if "the American side and those who support the U.S.A, in this sense, reject the use of force."
Russian Foreign Minister Sergey Lavrov told his French counterpart Laurent Fabius that it is unacceptable for the resolution to cite Chapter 7, his ministry said in a statement.
US Secretary of State John Kerry, in turn, said the US rejects a Russian suggestion that the UN endorsement come in the form of a non-binding statement from the Security Council president.
The US has to have a full resolution one that entails "consequences if games are played and somebody tries to undermine this," he said.
The 15-member UN Security Council cancelled plans for closed consultations on a Syria resolution.
The developments threatened what had been growing momentum toward a plan that would allow the Obama administration to back away from military action. Domestic support for a strike is uncertain in the United States, even as President Barack Obama seeks Congress' backing for action and there has been little international appetite to join forces against Assad.
The US and its allies have insisted Assad must be punished for an Aug. 21 chemical weapons attack outside Damascus that the Obama administration, France and others blame on the regime.
Damascus denies its forces were behind the attack. The US has said more than 1,400 Syrians died; even conservative estimates from international organisations put the toll at several hundred.
French Foreign Minister Laurent Fabius said the resolution must have teeth to ensure the Russian plan is not "used as a diversion.
French authorities "don't want to fall into a trap" that could allow Assad's regime to skirt accountability or buy time, he said. Syria's credibility in accepting the plan would be determined "by accepting these precise conditions."
He said the French draft resolution would demand Syria open its chemical weapons program to inspection, place it under international control, and ultimately dismantle it. A violation of that commitment, he said, would carry "very serious consequences." The resolution would condemn the attack and bring those responsible to justice, he said.
Obama threw his support behind the resolution. British Prime Minister David Cameron said his country would join France and the US in putting forward the proposal.
Russia, in turn, was working with Damascus on a detailed plan of action to be presented, Lavrov said. Russia will then be ready to finalise the plan with UN Secretary-General Ban Ki-moon and the Organization for the Prohibition of Chemical Weapons.
"We agreed to the Russian initiative as it should thwart the US aggression against our country," Syria's al-Moallem said.
Obama, who was to deliver a national address on Syria later today, cautiously welcomed the proposal. But he said the US is still prepared to go ahead with strikes if it falls through. He reached back into history and the Cold War rivalry between the United States and the Soviet Union to underline the need for enforcement.
"The key is, to paraphrase Ronald Reagan, that we don't just trust, but we also verify," Obama told CBS. "The importance is to make sure that the international community has confidence that these chemical weapons are under control, that they are not being used, that potentially they are removed from Syria and that they are destroyed."
Obama said the idea actually had been broached in his 20-minute meeting with Putin last week on the sidelines of an economic summit in St. Petersburg, Russia. Obama said he directed Kerry to have more conversations with the Russians and "run this to ground."
On Monday, Kerry said Assad could resolve the crisis by surrendering control of his chemical arsenal to the international community. Russia's Lavrov responded by promising to push Syria to place its chemical weapons under international control and then dismantle them quickly, to avert US strikes. Syria's acceptance came less than 24 hours later.
The Syrian National Coalition dismissed the Assad government's turnaround as a maneuver to escape punishment for a crime against humanity. The coalition had been hoping for military strikes from abroad to tip the balance in the war of attrition between rebels and Assad's forces.
In a statement Tuesday, the coalition said Moscow's proposal "aims to procrastinate and will lead to more death and destruction of the Syrian people."
"Crimes against humanity cannot be dropped by giving political concessions or by handing over the weapons used in these crimes," the group said.
Analysts cautioned that the details of how disarmament will be carried out that would make the plan credible.
"I don't think this proposal was developed and thought through. I think it came a little bit out of the blue to solve a political crisis," said Ralf Trapp, a disarmament consultant who worked for the Organization for the Prohibition of Chemical Weapons from 1997 to 2006. "Now we're in a situation where if we have political preparedness to go through with it, we now need to think in practical terms and that's where, as always, the devil is in the details."
Fabius also warned that finding and destroying "more than 1,000 tons of chemical weapons" would be very difficult and would require international verification amid Syria's civil war. He reiterated France's position that Assad must leave power: "We can't imagine that someone who was responsible for 110,000 dead, it is said, can stay in power forever."
Jean Pascal Zanders, an international disarmament expert, said any agreement depends on trust that the Syrian government is telling the truth about its weapons: "It requires full comprehensive declaration, and any failure on the Syrian government would immediately destroy confidence of the international community and probably split it again."