Momentum to avoid Western missile strikes on Syria has intensified after Bashar Assad's government accepted a plan to turn over its chemical weapons.
Meanwhile Britain, the United States and France agreed a resolution to be put to the UN Security Council today aimed at forcing Syria to make public its chemical weapons programme, place it under international control and dismantle it.
With domestic support for a strike uncertain in the United States and little international appetite to join forces against Assad, the developments had the potential to blunt a thorny diplomatic problem and allow the Obama administration to back away from military action.
But neither effort attempts to end or even address the civil war that has left more than 100,000 dead in Syria and the main opposition bloc dismissed the chemical weapons plan as a largely meaningless measure that would allow Assad free rein to fight on with conventional weapons.
Syria's foreign minister Walid al-Moallem said the government would accept a plan from Russia, its most powerful ally, to give up its chemical weapons in order "to thwart US aggression," offering a diplomatic response option.
His comments amounted to the first formal admissions by top Syrian officials that Damascus even possesses chemical weapons. In interviews aired as recently as Monday, Assad repeatedly refused to acknowledge whether his regime did.
Russia is now working with Damascus to prepare a detailed plan of action that will be presented soon, Foreign Minister Sergey Lavrov said. Russia will then be ready to finalise the plan with UN Secretary-General Ban Ki-moon and the Organisation for the Prohibition of Chemical Weapons.
President Barack Obama, scheduled to give a nationally televised address on Syria, reached back into history - and the Cold War rivalry between the United States and the Soviet Union - to make his case against Syria, even as he cautiously welcomed the early developments.
"The key is, to paraphrase Ronald Reagan, that we don't just trust, but we also verify," he 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."
He said the idea actually had been broached in his 20-minute meeting with Russian President Vladimir Putin last week on the sidelines of the economic summit in St. Petersburg. He said he told Secretary of State John Kerry to have more conversations with the Russians and "run this to ground."
The Syrian National Coalition dismissed the Assad government's turnaround as a manoeuvre 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.
It 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.
Syria's acceptance did not detail how any disarmament could be carried out, and analysts cautioned that it was those details that would make the offer credible.
But it was clear that many in the Middle East, Europe and the US were cautiously seizing on the initiative as a way to untangle the diplomatic impasse before Mr Obama takes the issue before Congress.
The UN Security Council has scheduled closed consultations on the joint resolution, scheduled for this evening.
Council diplomats said Russia asked for the meeting.