Syria’s chemical weapons must be destroyed or removed by mid-2014, under an agreement between the US and Russia.
US Secretary of State John Kerry outlined a six-point framework under which Syria must hand over a full list of its stockpile within a week.
If Syria fails to comply, the deal could be enforced by a UN resolution backed by the threat of sanctions or military force.
The US says the Syrian regime killed hundreds in a gas attack last month.
The government of Bashar al-Assad denies the allegations and has accused the rebels of carrying out the attack on 21 August.
In a joint news conference with Russian Foreign Minister Sergei Lavrov, Mr Kerry called on the Assad government to live up to its public commitments.
“There can be no room for games. Or anything less than full compliance by the Assad regime,” he said.
Mr Kerry and Mr Lavrov said if Syria failed to comply, then a UN resolution would be sought under Chapter VII of the UN charter, which allows for the use of force.
Russia and the US have agreed on an assessment that the Syrian government possesses 1,000 tonnes of chemical agents and precursors, according to a US official.
The US believes the materials are located in 45 sites, all in regime hands, half of which have useable quantities of chemical agents, the official added.
BBC’s Paul Adams: ‘A remarkable agreement’
However, it is thought that Russians have not agreed the number of sites, nor that they are all under control.
Mr Kerry said inspectors must be on the ground by November, and that the stockpiles should be removed or destroyed by mid-2014.
The six points outlined by Mr Kerry were:
- The amount and type of chemical weapons must be agreed and “rapidly” placed under international control
- Syria must submit within one week a comprehensive listing of its stockpiles
- Extraordinary procedures under the Chemical Weapons Convention will allow “expeditious destruction”
- Syria must give inspectors “immediate, unfettered access” to all sites
- All chemical weapons must be destroyed, including the possibility of removing weapons from Syrian territory
- UN will provide logistical support, and compliance would be enforced under Chapter VII
France, which was the only country willing to join the US in taking military action in Syria, welcomed the agreement.
Foreign Minister Laurent Fabius said it was an “important advance”.
However, the military leader of the anti-Assad Free Syrian Army rejected the deal and promised to continue fighting.
“There is nothing in this agreement that concerns us,” said Gen Salim Idriss, describing it as a Russian initiative designed to gain time for the Syrian government.
Mr Kerry said he hoped the deal would help kick-start a wider peace process.
“We could also lay the groundwork for further co-operation that is essential to end the bloodshed that has consumed Syria for more than two years,” he said.
“What we agreed on here today could conceivable be the first critical concrete step in that direction.”
Mr Lavrov suggested there could be another international peace conference on Syria by October.
“The main thing is to make sure that all Syrian sides are represented at the conference,” he said.
Over the years there have been several conferences, some of which have included the Syrian opposition and excluded the government.
More than 100,000 people have died since the uprising against President Assad began in 2011.
Millions of Syrians have fled the country, and millions more have been left homeless by the fighting.