US secretary of state John Kerry and Russian foreign minister Sergey Lavrov have reached an agreement on a framework for securing Syria's chemical weapons after the third day of their intense negotiations in Geneva.
They say some elements of the deal include a timetable and how Syria must comply - and that if Syria fails, they will seek a Security Council resolution that could authorise military action.
At a news conference, Mr Kerry said the pair and their teams of experts had reached "a shared assessment" of the existing stockpile and that Syria must destroy all of its weapons. Mr Kerry said "we have committed to a standard that says, verify and verify".
The negotiations between the United States and Russia on securing Syria's chemical weapons are considered key to a resumption of peace talks to end the civil war in the country. Mr Kerry said they had agreed on grounds under which they might request a Security Council "Chapter 7" resolution authorising both military and non-military sanctions.
The US and Russia are two of the five permanent Security Council members with a veto. The others are Britain, China, and France.
Mr Kerry said any violations will result in "measures" from the Security Council, while Mr Lavrov said the violations must be sent to the Security Council from the board of the chemical weapons convention before sanctions - short of the use of force - would be considered.
At a news conference at the Intercontinental Hotel in Geneva, Mr Kerry said the inspectors must be on the ground by November and destruction or removal of the chemical weapons must be completed by mid-2014.
Mr Lavrov called the agreements a "decision based on consensus and compromise and professionalism".
Meanwhile, al Qaida-affiliated rebels battled more moderate Syrian opposition fighters in a town along the Iraqi border, killing at least five people in the latest outbreak of infighting among the forces opposed to President Assad.
Clashes between rebel groups, particularly pitting al Qaida-linked extremist factions against more moderate units, have grown increasingly common in recent months, undermining the opposition's primary goal of overthrowing Assad. The Britain-based Syrian Observatory for Human Rights said the latest fighting took place in the town of Boukamal between the Islamic State in Iraq and the Levant against more mainstream rebel groups.