The United States and Russia agreed on Saturday on a proposal to eliminate Syria's chemical weapons arsenal, averting the possibility of any immediate U.S. military action against President Bashar Assad's government.
U.S. Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov announced the agreement after nearly three days of talks in Geneva.
Kerry said that under the pact, Syria must submit a "comprehensive listing" of its chemical weapons stockpiles within one week.
He told a news conference with Lavrov that U.N. weapons inspectors must be on the ground in Syria no later than November. The goal, he said, was the complete destruction of Syria's chemical weapons by the middle of 2014.
Kerry said that if Syria did not comply with the agreement, which must be finalized by the Organization for the Prevention of Chemical Weapons, it would face consequences under Chapter 7 of the U.N. Charter, the part that covers sanctions and military action.
There was no agreement on what those measures would be. U.S. President Barack Obama reserves the right to use military force in Syria, Kerry said.
"There's no diminution of options," Kerry said.
Lavrov said of the agreement: "There (is) nothing said about the use of force and not about any automatic sanctions."
Obama had threatened the use of force in response to an Aug. 21 chemical weapons attack in Syria that U.S. officials say killed about 1,400 people. The
United States has blamed Assad's government for the attack, while Russia and Assad say it was the work of rebel forces.
Despite the diplomatic breakthrough, chemical weapons only account for around 2 percent of deaths in a civil war in which 100,000 people have been killed.
On Saturday, Syrian warplanes struck against rebel-held suburbs of the capital Damascus and government forces clashed with rebels on the frontlines, according to residents.
The residents and opposition activists asked about the deal said that it would not benefit normal Syrians.
"The regime has been killing people for more than two years with all types of weapons. Assad has used chemical weapons six or seven times. The killing will continue. No change will happen. That is it," said an opposition activist in a rebel-held suburb of Damascus who uses the name Tariq al-Dimashqi.
"The most important point is the act of killing, no matter what is the weapon," he said.
Syrian state media broadcast the Kerry and Lavrov news conference live, indicating that Damascus is satisfied with the deal.
U.N. Secretary-General Ban Ki-moon said earlier that a report by U.N. chemical weapons experts would confirm that poison gas was used in the Aug. 21 attack.
Ban also said that Assad "has committed many crimes against humanity", although he did not say whether it was Assad's forces or rebels who used the gas.
The original drive for a political solution to the conflict, dubbed the "Geneva Plan" and calling for a transitional government, went nowhere as Assad refused to cede power and the opposition insisted he could not be a part of any new political order.
The latest talks prompted Obama to put on hold his plans for U.S. air strikes in response to the chemical weapons attack. Obama is now also spared facing a vote in Congress on military action that he had appeared increasingly likely to lose at this stage.
Experts say removing Syria's hundreds of tonnes of chemical weapons, scattered in secret installations, will pose huge technical problems in the middle of a civil war.