Russia and the United States put aside bitter differences over Syria this month to strike a deal to remove President Bashar al-Assad's chemical arsenal and avert U.S. military action against him.
But efforts to forge a U.N. Security Council resolution endorsing that plan have run into difficulties due to disagreements between Russia on one side and the United States, Britain and France on the other, U.N. diplomats say.
The U.S.-Russia deal came after an Aug. 21 sarin gas attack near Damascus that Washington says killed over 1,400 people, many of them children. Following are questions and answers about the plan to dismantle Syria's poison gas program.
WHAT IS THE SIZE OF SYRIA'S CHEMICAL ARSENAL?
Syria has roughly 1,000 tonnes of chemical toxins - including mustard gas and the nerve agents sarin and VX - spread over as many as 50 sites around the country.
WHAT HAPPENS AT THE HAGUE'S CHEMICAL ARMS AGENCY?
The 41-member Executive Council of the Organization for the Prohibition of Chemical Weapons (OPCW) in The Hague is expected to vote on Tuesday on a joint Russian-American proposal to rapidly verify and destroy Syria's chemical weapons stockpile. That vote has been repeatedly delayed.
According to the U.S.-Russia framework agreement, the chemical arms agency's Executive Council will detail "special procedures for expeditious destruction of the Syrian chemical weapons program and stringent verification thereof."
The chemical arms agency's decision must be approved by a simple majority of council members, though agreement is almost always reached through a consensus, which is expected in Syria's case. The council meets behind closed doors but may be open to observer countries that are not yet members. Syria is not yet a full member.
Syria acceded to the Chemical Weapons Convention this month in line with the U.S.-Russia deal. Its accession to the treaty comes into force in October.
WHAT ARE KEY DEADLINES UNDER THE U.S.-RUSSIA DEAL?
On Saturday, the one-week limit for Syria to present a complete list of its chemical weapons program lapsed. Syria submitted the list to the OPCW, the agency said.
By Nov. 30, inspectors from The Hague's chemical arms agency are due to have completed on-site inspections of locations declared by Syria.
Nov. 30 is also the deadline for destruction of chemical weapons production and mixing/filling equipment.
By June 30, 2014, the destruction of the entire Syrian chemical weapons arsenal is due to be completed.
HOW WILL THE REMOVAL OF SYRIA'S ARSENAL BE FUNDED?
U.S. Secretary of State John Kerry said in Geneva that Washington and Moscow would help fund the dismantling of Syria's chemical arsenal. He added that "we will seek, in the process of the U.N. and in the effort to have a global commitment to this, help from many other of our international partners."
European Union sources said the bloc was looking into providing some financial assistance. Assad said the process of destroying his chemical arsenal would cost $1 billion.
WHO WILL REMOVE AND DESTROY THE CHEMICAL WEAPONS?
That is still being worked out. However, OPCW and U.N. experts would be involved. American and Russian experts may also participate. The actual destruction and/or removal of the weapons will be complicated by Syria's civil war. More than 100,000 people have been killed in the conflict, which grew out of a 2011 uprising against Assad.
The Hague-based chemical arms agency has never moved weapons across borders before, because of the risk, and never worked in a war zone.
WHAT HAPPENS AT THE SECURITY COUNCIL?
As soon as the OPCW decision is made, the full Security Council will begin negotiations on a resolution intended to support the OPCW Executive Council's decision. The five permanent Security Council members have been negotiating a draft resolution.
If the OPCW decision comes on Tuesday, U.N. diplomats say a Security Council resolution could be put to a vote in New York on Thursday on the sidelines of the annual gathering of world leaders for the General Assembly session that begins on Tuesday.
WHAT WILL THE RESOLUTION DO?
Western officials say the point of the resolution is to make the Russian-American plan agreed to in Geneva legally binding and enforceable. Russia, however, has said that the resolution has a more modest purpose - simply to back the OPCW decision.
WHAT IS THE MAIN STICKING POINT?
Enforceability. The United States, Britain and France want the measures in the resolution to be legally binding and enforceable under Chapter 7 of the U.N. charter. Chapter 7 outlines mechanisms for enforcement, which include diplomatic and economic sanctions as well as military intervention.
Russia has rejected the idea of using a Chapter 7 resolution to make the agreement legally binding and enforceable. It says that could open the door to an Iraq- or Libya-style foreign military operation.
Diplomats said the current draft reflects the language of the U.S.-Russia framework agreement approved in Geneva. That agreement said that "in the event of non-compliance, including unauthorized transfer, or any use of chemical weapons by anyone in Syria, the Security Council should impose measures under Chapter VII of the U.N. Charter."
Russian Foreign Minister Sergei Lavrov said on Sunday: "The U.N. Security Council may adopt a strong resolution in support of the decision of the OPCW, but it will not be under Chapter 7, and accordingly, it won't be possible to use it to implement ... unilateral military action against Syria."
In other words, any punitive measures would require a new resolution under Chapter 7 of the U.N. Charter. That means Russia could block any such measures.
France's foreign minister said on Monday he expects the Security Council to agree on a resolution to enforce the chemical weapons deal with Syria and appeared to back off French calls for the measure to threaten the use of force against Assad.
U.N. diplomats say it is possible Russia and the Western powers will fail to agree on a draft resolution this week. Russia has already vetoed three resolutions that condemned Assad's government and threatened it with sanctions.
WHAT HAPPENS IF SYRIA FAILS TO COMPLY?
Lavrov told reporters after the framework agreement that the idea that noncompliance should be punished "does not mean that every violation that will be reported to the Security Council will be taken by word."
He also said that Russia would support a new council resolution imposing punitive measures on whoever is guilty of noncompliance only when there is "100 percent" certainty about the circumstances of the violation.
Any punitive measures would require a new resolution. Moscow, Assad's chief ally, has made clear it would oppose any threat of force in the event of Syrian noncompliance.
COULD THE U.S. ATTACK SYRIA WITHOUT U.N. APPROVAL?
Yes, but some analysts and diplomats say air strikes against Syria without Security Council approval would be illegal. The United States has done it before, as in the case of the 1999 Kosovo war, when it circumvented the Security Council and joined NATO allies in a U.S.-led bombing campaign to drive Serbian troops out of Kosovo.
U.S. President Barack Obama has said repeatedly that he is prepared to act against Syria without a U.N. mandate if diplomacy fails. He put a congressional vote to authorize the use of force in Syria on hold while the current diplomatic process plays itself out.